Dept. of Env. v. Carroll Cnty. Frederick Cnty. v. Dept. of Env.

Maryland Department of the Environment v. County Commissioners of Carroll County,

Maryland

No. 5, September Term 2018

Frederick County, Maryland v. Maryland Department of the Environment

No. 7, September Term 2018

Environmental Law – Administrative Law – Clean Water Act – Stormwater

Discharge Permits – Impervious Surface Restoration. The Maryland Department of the

Environment may lawfully include an impervious surface restoration requirement in a

municipal separate storm sewer system (MS4) discharge permit without reference to the

“maximum extent practicable” standard in the federal Clean Water Act for certain pollution

controls. The Department was not arbitrary or capricious in deciding to include such a

provision in Frederick County’s most recent MS4 permit. 33 U.S.C. §1342(p)(3)(B)(iii);

Maryland Code, Environment Article, §9-322 et seq.

Environmental Law – Administrative Law – Clean Water Act – Stormwater

Discharge Permits – Scope of MS4 Permit. The Maryland Department of the

Environment may lawfully include an impervious surface restoration requirement in a

municipal separate storm sewer system (MS4) discharge permit when that requirement is

derived from commitments in the State Watershed Implementation Plan that were accepted

by the federal Environmental Protection Agency (EPA) when it adopted the Chesapeake

Bay TMDL, which in turn allocated pollutant reductions among various sources of

pollution for the purpose of achieving water quality standards in the Chesapeake Bay, in

compliance with the federal Clean Water Act. To the extent that other restoration

requirements in a permit are based on pollutant reduction allocation decisions made in other

EPA-approved TMDLs, any challenge to those decisions should have been made in

connection with the EPA’s approval of the TMDLs themselves and cannot be made as part

of judicial review in State court of a permit issued by the Department. 33 U.S.C. §1342(p);

Maryland Code, Environment Article, §§1-606, 9-322 et seq.

Environmental Law – Administrative Law – Clean Water Act – Stormwater

Discharge Permits – Classification of Phase I Jurisdictions. The Maryland Department

of the Environment had authority to treat Frederick County and Carroll County as Phase I

jurisdictions for purposes of their municipal separate storm sewer system (MS4) discharge

permits. It was not arbitrary or capricious for the Department to classify Carroll County

as a Phase I jurisdiction without also including Washington County in that category. 33

U.S.C. §1342(p)(1)-(2); Maryland Code, Environment Article, §9-322 et seq.

Environmental Law – Administrative Law – Clean Water Act – Stormwater

Discharge Permits – Water Quality Trading. A potential compliance method in a

municipal separate storm sewer system (MS4) discharge permit could authorize the

permittee to engage in water quality trading. Water quality trading occurs when a permittee

takes credit for a pollution reduction accomplished by another entity that the permittee

compensates. It was not arbitrary or capricious for the Maryland Department of the

Environment to omit water quality trading from an MS4 permit until it had finally adopted

regulations that it had proposed concerning that compliance method. 33 U.S.C. §1342(p);

Maryland Code, Environment Article, §9-322 et seq.

Environmental Law – Administrative Law – Clean Water Act – Stormwater

Discharge Permits – Permit Provision Related to Comprehensive Plan. The Maryland

Department of the Environment included a provision in municipal separate storm sewer

system (MS4) discharge permits requiring the permittees to cooperate with other agencies

during completion of the water resources element of the local comprehensive plan required

by a Maryland statute. The permit provision stated that such cooperation “shall not be

restricted by the responsibilities attributed to other entities by separate State statute,

including but not limited to reviewing and approving plans and appropriating funds.”

While the language of this provision is ambiguous, it does not, and could not, transfer the

responsibilities of other agencies to the permittee. 33 U.S.C. §1342(p); Maryland Code,

Environment Article, §9-322 et seq.; Land Use Article, §3-101 et seq.

Circuit Court for Carroll County

Case No. 06-C-15-068141

IN THE COURT OF APPEALS

Circuit Court for Frederick County OF MARYLAND

Case No. 10-C-15-000293

Nos. 5 & 7

Argued: September 13, 2018

September Term, 2018

MARYLAND DEPARTMENT OF THE ENVIRONMENT

V.

COUNTY COMMISSIONERS OF CARROLL COUNTY,

MARYLAND

FREDERICK COUNTY, MARYLAND

V.

MARYLAND DEPARTMENT OF THE ENVIRONMENT

Barbera, C.J.,

*Greene

*Adkins

McDonald

Watts

Hotten

Getty,

JJ.

Opinion by McDonald, J.

Watts, Hotten, and Getty, JJ., dissent.

Filed: August 6, 2019

*Greene and Adkins, JJ., now retired,

Pursuant to Maryland Uniform Electronic Legal

Materials Act

participated in the hearing and conference of this

(§§ 10-1601 et seq. of the State Government Article) this document is authentic.

case while active members of this Court; after

2019-08-06 13:11-04:00 being recalled pursuant to the Maryland

Constitution, Article IV, Section 3A, they also

participated in the decision and adoption of this

Suzanne C. Johnson, Clerk opinion.

In the quest to conserve a vital resource – the nation’s waters – Congress has enlisted

the federal, state, and local governments under the Clean Water Act (“the Act”)1 in a

regulatory approach sometimes called “cooperative federalism.” This effort involves a

type of regulation that takes the form of a “permit” issued by a federal agency (or a state

agency with federal oversight) at specified intervals to the regulated entity. Such permits

authorize discharges of pollution into waterways, which the Act otherwise prohibits. When

the targeted pollution is in stormwater, the permittee – i.e., the regulated entity – is often a

local government. Inevitably, as in any assignment of responsibility for solving a serious

problem, there is disagreement as to the solution and the allocation of that responsibility.

One way to resolve such disputes is through judicial review of the permit.

This consolidated appeal concerns judicial review of the most recent permits issued

to Carroll County and Frederick County (“the Counties”) under the Act and a parallel

Maryland regulatory scheme. The permits regulate the discharge of polluted stormwater

into waterways in the Chesapeake Bay watershed. The permits were developed and issued

by the Maryland Department of the Environment (“Department”) under the supervision of

the United States Environmental Protection Agency (“EPA”), as part of an EPA-led, multi-

state effort to restore the Chesapeake Bay in compliance with the Act.

1

33 U.S.C. §1251 through §1388.

Both Counties raise serious issues concerning the scope of the permits, the level of

effort required of each County, the classification of the Counties (which affects certain

conditions in the permits), and the absence or inclusion of certain terms in the permits.

Ultimately, we hold that the Department did not exceed its authority under State and federal

law when it issued the permits, nor did it act arbitrarily or capriciously in including the

challenged terms in the permits.

I

Background

A. The Clean Water Act and Stormwater Controls for the Chesapeake Bay

The Chesapeake Bay lies between the western and eastern shores of Maryland and

Virginia. As a recent federal court opinion has noted, its name derives from the Algonquin

word for “great shellfish bay.” Norfolk Southern Railway Co. v. City of Roanoke, 916 F.3d

315, 323 (4th Cir. 2019) (Wilkinson, J., concurring). While the Bay once hosted a quantity

of fish and shellfish described as “unbelievable, ... indescribable, and ...

incomprehensible,” that is no longer the case and “[i]nstead of fish, we quantify

phosphorus, nitrogen, sediment, and other pollutants” that threaten the health of the Bay’s

marine life. Id.

The watershed of the Chesapeake Bay – the land from which water drains into it –

covers about 64,000 square miles in six states and the District of Columbia (“the Bay

States”), and extends from Cooperstown, New York, to Norfolk, Virginia. Pollution from

that region contaminates the waters that feed the Bay and ultimately the Bay itself.

“Restoring damaged waters like the Chesapeake Bay requires sustained effort, entailing

2

cooperation and coordination among the federal government, state and local governments,

the enterprise of the private sector, and all the people who make this region their home.”

Norfolk Southern, 916 F.3d at 323 (internal quotation marks and citation omitted).

Federal, state, and local governments have spent decades devising programs to

reduce the pollution that enters the Bay. This appeal concerns one such program. In any

effort to describe a complex regulatory regime, overseen by various government agencies,

one inevitably must become familiar with the concepts, jargon, and acronyms that define

that effort. We begin with an overview of the key elements pertinent to this appeal.

Where Pollutants Come From – Point and Nonpoint Sources

An important distinction for purposes of the Clean Water Act is the difference

between “point sources” and “nonpoint sources” of water pollution. Point sources are

discrete and localized, like a pipe carrying discharges from a factory or wastewater

treatment plant.2 Nonpoint source pollution, by contrast, comes from dispersed areas like

farms or fields where water runs off the land without being collected or channeled into a

point source.3 This distinction matters for purposes of the Act because the federal statute

regulates point sources of water pollution but does not directly regulate nonpoint sources.

2

A “point source” is defined as “any discernible, confined and discrete conveyance,

including but not limited to any pipe, ditch, channel, [or other types of conveyance], from

which pollutants are or may be discharged.” 33 U.S.C. §1362(14).

3

“Nonpoint source” is not defined in the Act. The EPA regards a “nonpoint source”

as “any source of water pollution that does not meet the legal definition of ‘point source’

in [the Act].” See EPA, Basic Information about Nonpoint Source (NPS) Pollution,

https://perma.cc/QPW5-LADC.

3

Discharge Permits

The Act generally prohibits “any person”4 from discharging pollutants from a point

source into a waterway.5 33 U.S.C. §1311(a). Accordingly, the statute requires a permit

for the discharge of pollutants into a water body from a point source under specified

conditions. The Act establishes the National Pollution Discharge Elimination System

(“NPDES”) to govern such permits. 33 U.S.C. §1342. The EPA is authorized to issue and

enforce these permits. 33 U.S.C. §§1319, 1342(a)(1). The EPA may also delegate that

authority to a state so long as the state’s law establishes a parallel permitting program

consistent with the Act. 33 U.S.C. §1342(b). The EPA has delegated such authority to

most states, including Maryland.6

Each discharge permit in Maryland is issued under the Act and under a parallel State

program. See Maryland Code, Environment Article (“EN”), §9-322 et seq.; COMAR

26.08.04.07. Under Maryland law, the Department is the agency designated to issue and

enforce these permits. EN §9-253; COMAR 26.08.04.01. Permits are generally issued for

fixed terms of five years or less, subject to renewal. See 33 U.S.C. §1342(b)(1)(B); EN

4

Under the Act, “person” includes “an individual, corporation, partnership,

association, State, municipality, commission, or political subdivision of a State, or any

interstate body.” 33 U.S.C. §1362(5).

5

“Discharge of a pollutant” means “any addition of any pollutant to navigable

waters from any point source [or] any addition of any pollutant to the waters of the

contiguous zone or the ocean from any point source other than a vessel or other floating

craft.” 33 U.S.C. §1362(12).

6

See EPA, NPDES Permits Around the Nation, https://perma.cc/2VF2-C7MK.

4

§9-328(b). As a general rule, the Act prohibits subsequent permits from containing “less

stringent” conditions than the conditions in the previous permit – sometimes referred to as

the “anti-backsliding prohibition” in the Act. 33 U.S.C. §1342(o).

The Act does not require permits for nonpoint sources or otherwise directly regulate

them. Accordingly, the EPA does not regulate those sources of water pollution. States

may do so through their own regulatory programs, as Maryland has done.7 The Act

authorizes federal grants to assist the states in such efforts. 33 U.S.C. §1288.

Pollution Controls in Permits – Water Quality Standards and Effluent Limitations

Under the Act, “water quality standards” are the benchmark for clean water. For

each water body covered by the Act, states submit water quality standards to the EPA for

review and approval.8 The standards are to be based on the water body’s “designated use”

(e.g., public water supply, fishing, recreational use) and include criteria necessary to

support that use (e.g., specific limits on certain pollutant concentrations). See 33 U.S.C.

§1313(c)(2)(A); 40 CFR §§130.3, 131.6; COMAR 26.08.02.01-.03.

7

The State relies on a “wide array of nonpoint source pollution control programs

[to combat] these varied pollution sources.” Maryland Department of the Environment,

Nonpoint Source Program (319) Management and Financial Assistance,

https://perma.cc/X6ZV-6T5E. Such programs include septic system upgrades, erosion and

sediment control on farms, fertilizer application management, and many others. See

Maryland Department of the Environment, Maryland’s 2015-2019 Nonpoint Source

Management Plan (updated August 4, 2016), available at https://perma.cc/RR5K-6EMB.

8

If the EPA does not approve a state-authored water quality standard, the EPA must

establish the standard itself. 33 U.S.C. §1313(c)(4).

5

To achieve water quality standards, the Act requires that discharge permits include

pollution controls for point sources. 33 U.S.C. §1311(b). The Act calls these controls

“effluent limitations” – “effluent” being the material discharged by a point source.9

Effluent limitations may be “technology based” or “water quality based.” See EPA,

NPDES Permit Limits, https://perma.cc/L4G6-24K9; Natural Resources Defense Council

v. EPA, 808 F.3d 556, 563 (2d Cir. 2015).

Technology based effluent limitations are generally the first round of controls in the

effort to achieve water quality standards. See 33 U.S.C. §1311(b)(1)(A). They “represent

the minimum level of control that must be imposed in a permit[.]” 40 CFR §125.3(a). But

even the most stringent technology based effluent limitations have not achieved water

quality standards in thousands of the nation’s waterways.10 Congress anticipated this

possibility in 1972 by retaining water quality standards “as a supplementary basis for

effluent limitations … so that numerous point sources, despite individual compliance with

effluent limitations, may be further regulated to prevent water quality from falling below

acceptable levels.” EPA v. California ex rel. State Water Resources Control Board, 426

U.S. 200, 205 n.12 (1976). If technology based limitations do not achieve the water quality

The term “effluent” is not defined in the Act. However, the Act defines “effluent

9

limitation” as “any restriction established by a State or the [EPA] on quantities, rates, and

concentrations of chemical, physical, biological, and other constituents which are

discharged from point sources into navigable waters, the waters of the contiguous zone, or

the ocean, including schedules of compliance.” 33 U.S.C. §1362(11).

10

See American Farm Bureau Federation v. EPA, 792 F.3d 281, 289-91 (3d Cir.

2015).

6

standards, permits may include “any more stringent limitation ... necessary to meet water

quality standards” – i.e., “water quality based effluent limitations.” 33 U.S.C.

§1311(b)(1)(C); 40 CFR §130.7(c).11 Thus, regardless of whether a waterway is over-

polluted due to point sources, nonpoint sources, or some mixture of both, the Act authorizes

the imposition of water quality based controls on point sources, in addition to the most

stringent technology based controls.12

These two types of effluent limitations differ in their reference point and in their

strategies for reducing pollution.13 For technology based limitations, the reference point is

the source, and the strategy is to deploy pollutant-reducing technology at that source

regardless of its contribution of pollutants to the waterway. By contrast, for water quality

based effluent limitations, the reference point is the waterway, and the strategy is for the

11

Cf. COMAR 26.08.03.01C(2)(b) (“Best available technology shall be required as

the minimum for all permitted discharges. If it is determined that compliance with the

established water quality standards will not be achieved through [best available

technology], additional treatment shall be [required].”).

12

A core premise of water quality based effluent limitations in general is that

permitting agencies may require point sources to go beyond their existing capabilities to

achieve further pollution reductions. See Natural Resources Defense Council v. EPA, 915

F.2d 1314, 1316-17 (9th Cir. 1990).

13

See Michael P. Healy, Still Dirty After Twenty-Five Years: Water Quality

Standard Enforcement and the Availability of Citizen Suits, 24 Ecology L.Q. 393, 399

(1997) (“Technology-based standards are based on the source’s technological capacity to

control pollution, while water quality-based standards are based on the environmental

effect of the discharged pollution.”).

7

point source to implement any additional actions (beyond the already required

technologies) necessary to achieve the applicable water quality standard.14

The Point Sources Here – Municipal Separate Storm Sewer Systems (MS4s)

This appeal concerns permits for a type of point source known as a “municipal

separate storm sewer system” (“MS4”).15 An MS4 is a network of conveyances (including

storm drains, gutters, and other drainage systems) designed to carry only stormwater (as

opposed to a “combined sewer system” that conveys both sanitary sewage and stormwater).

40 CFR §122.26(b)(8).

MS4s differ from typical “end-of-pipe” point sources in certain respects. A

common point source, such as a pipe that discharges waste from a factory, usually

discharges a known and finite set of pollutants from a specific location. By contrast,

stormwater picks up various pollutants as it flows across widely dispersed areas, including

paved (or “impervious”) surfaces, on its way to one of the many conveyances that make up

an MS4, and then into a waterway. The quantity of stormwater that flows through these

14

See EPA, NPDES Permit Writer’s Manual (September 2010) (“EPA Permit

Writer’s Manual”), available at https://perma.cc/P8BX-MNUY, at 5-1 (Technology based

effluent limitations “are developed independently of the potential impact of a discharge on

the receiving water, which is addressed through water quality standards and water quality-

based effluent limitations[.]”).

15

Shortly after the passage of the Clean Water Act in the 1970s, the question of

whether – and if so, how – to treat MS4s as point sources under the Act generated

regulations and litigation. The EPA initially adopted regulations exempting MS4s from

the Act’s permit requirement. That exemption was challenged and held invalid in Natural

Resources Defense Council v. Costle, 568 F.2d 1369, 1372-73 (D.C. Cir. 1977).

Ultimately, Congress enacted the Water Quality Act of 1987, which explicitly established

a discharge permit requirement for MS4s. See 33 U.S.C. §1342(p).

8

conveyances into a waterway can vary unpredictably depending on the weather, any

development of the land (e.g., whether the land is paved), and other activities on the land

(e.g., litter, use of lawn fertilizers).

Given these differences between an MS4 and a typical point source like a factory, a

discharge permit for an MS4 differs from that for a typical point source. A discharge permit

for a typical end-of-pipe point source usually sets numeric limits as effluent limitations for

the known set of pollutants discharged from that pipe.16 Using that same approach for an

MS4 would entail setting effluent limitations for each conveyance within the stormwater

drainage system, which would be administratively, technically, and financially

burdensome.17 Instead, an MS4 permit generally requires the permittee to implement

flexible management programs designed to reduce the pollution introduced into

16

EPA Permit Writer’s Manual, supra note 14, Ch. 5 (explaining in detail a

permitting agency’s process for developing technology based effluent limitations); Natural

Resources Defense Council v. EPA, 808 F.3d 556, 567 (2d Cir. 2015) (A discharge permit

imposes effluent limitations on a point source “based on how much technology is able to

reduce the amount of a pollutant at issue”).

17

See EPA, National Pollutant Discharge Elimination System Permit Application

Regulations for Storm Water Discharges, 55 Fed. Reg. 47990, 48037-38 (November 16,

1990) (“EPA Preamble to 1990 Phase I MS4 Rule”). The discussion of the background of

the regulations that appears together with the notice announcing the EPA’s final adoption

of the regulations is sometimes informally referred to as a “preamble” to the regulations.

However, it is not itself part of the regulations and does not appear in the Code of Federal

Regulations. See James T. O’Reilly, Administrative Rulemaking §10:1 (2019 ed.).

9

stormwater, thereby limiting the amount of pollution discharged into the waterway.18 In

the language of the Act, an MS4 permit is to include “controls to reduce the discharge of

pollutants to the maximum extent practicable, including management practices, control

techniques and system, design and engineering methods, and such other provisions as the

[EPA] or the State determines appropriate for the control of such pollutants.” 33 U.S.C.

§1342(p)(3)(B)(iii).

Implementation of the MS4 Permit Requirement – Phase I and Phase II

The Act and related EPA regulations have applied the permit requirement to MS4s

in two phases. The first phase (“Phase I”) took effect during the period 1987-94 and

included stormwater systems that were serving more heavily populated areas – dubbed

“large” and “medium” MS4s – and those that were contributing to the failure of a water

body to meet water quality standards, irrespective of the size of the population served. See

33 U.S.C. §1342(p)(2); 40 CFR §122.26(b). Subsequently, a second phase (“Phase II”)

covered “small” MS4s. See 33 U.S.C. §1342(p)(5)-(6); 40 CFR §122.34. As a general

rule, permits for MS4s included in Phase I have been subject to an earlier timetable and

more stringent conditions than permits for MS4s included in Phase II.

18

See EPA Preamble to 1990 Phase I MS4 Rule, 55 Fed. Reg. at 48037-38; Natural

Resources Defense Council v. New York State Dep’t of Envtl. Conservation, 34 N.E.3d

782, 787 (N.Y. 2015).

10

Total Maximum Daily Load (TMDL)

An important element in determining the conditions that appear in a discharge

permit is what is known as the “total maximum daily load” – or “TMDL.” The Clean

Water Act does not define this phrase, but describes it as the “level” of a pollutant that a

water body can tolerate without violating applicable water quality standards. 33 U.S.C.

§1313(d)(1)(C). In practice, the acronym “TMDL” has come to refer to more than just a

numeric measure of a pollutant. It has also come to refer to the process and calculations

used to determine that level of a pollutant and its allocation among sources of the pollutant.

The document in which an agency calculates the TMDL, in the sense of a numeric measure

of a pollutant, and allocates that level among various sources of pollution is also sometimes

referred to as a “TMDL.” A singularly complex example pertinent to this case is what is

referred to as the Chesapeake Bay TMDL (“Bay TMDL”),19 which is discussed in greater

detail below.

The EPA has elaborated on the meaning of TMDL as a numeric measure of pollution

in its regulations. The term “load” refers to a measure of water pollution. See 40 CFR

§130.2(e) (defining “load” as “[a]n amount of matter or thermal energy that is introduced

into a receiving water”). The phrase “total maximum daily load” or “TMDL” is defined in

regulation as “the sum of” amounts of the relevant pollutant emanating from various point

and nonpoint sources together with a “natural background” amount of the pollutant and a

19

EPA, Chesapeake Bay Total Maximum Daily Load for Nitrogen, Phosphorus and

Sediment (December 29, 2010), available at https://perma.cc/RWM2-Y22N.

11

“margin of safety.” 40 CFR §§130.2(i), 130.7(c)(1). A TMDL, in this sense, “can be

expressed in terms of either mass per time, toxicity, or other appropriate measure….” 40

CFR §130.2(i). To understand this definition of TMDL as a numeric measure requires an

understanding of the TMDL process.

The TMDL process is based on the direction in the Act that each state identify

waterways for which technology based effluent limitations are not achieving water quality

standards.20 33 U.S.C. §1313(d)(1)(A). If water quality standards are not being met in a

waterway due to excess levels of a particular pollutant, the state is to determine the

maximum amount of that pollutant that the waterway can receive without violating water

quality standards – i.e., the TMDL for that pollutant as to that waterway. 33 U.S.C.

§1313(d)(1)(C). The resulting TMDL – as a cap on the pollutant – is sometimes referred

to as a “pollution budget” or “pollution diet.” E.g., Norfolk Southern, 916 F.3d at 324;

Conservation Law Foundation v. EPA, 964 F. Supp. 2d 175, 179 (D. Mass. 2013).

The EPA’s regulations recognize that, in order for a state to calculate the maximum

level of a pollutant that a waterway can tolerate without violating water quality standards,

a state agency must conduct a complex scientific analysis. The state agency must consider,

among other things, the relationship between the water quality standards and the level of

the pollutant in the waterway, the various sources of the pollutant, and the extent to which

20

As indicated above, when technology based effluent limitations are inadequate to

achieve water quality standards, discharge permits may include water quality based

effluent limitations.

12

each source contributes to the violation of water quality standards. See 40 CFR §130.7(c).

As indicated earlier, in developing the TMDL for that pollutant, the agency must also factor

in “seasonal variations and a margin of safety which takes into account any lack of

knowledge concerning the relationship between effluent limitations and water quality.” 33

U.S.C. §1313(d)(1)(C).

Once the agency produces its best estimate of the maximum pollutant level

consistent with water quality standards – i.e., the TMDL in the sense of a numeric measure

of pollution – it must then apportion that amount to the relevant sources of that pollution

while allowing for the margin of safety required by the Act. See 40 CFR §§130.2(i),

130.7(c). The portion assigned to each relevant point source is called a “wasteload

allocation.” 40 CFR §130.2(h). The portion assigned to each nonpoint source is called a

“load allocation.” 40 CFR §130.2(g). In all, therefore, the TMDL – in the sense of a

numeric amount – for a given pollutant for a particular waterway is the sum of the

wasteload allocations, the load allocations, the natural background, and the margin of

safety. 40 CFR §§130.2(i), 130.7(c)(1). After a state has determined a TMDL for a

particular pollutant with respect to a particular waterway, it is to be submitted to the EPA

for approval. 33 U.S.C. §1313(d)(2).

When a state submits a TMDL to the EPA, the state provides not only the maximum

pollutant amount, but also the various wasteload allocations and load allocations, together

with an explanation of the calculations that resulted in that maximum amount and the

allocations. EPA, Water Quality Planning and Management, 50 Fed. Reg. 1774, 1775

(January 11, 1985) (“it is impossible to evaluate whether a TMDL is technically sound and

13

whether it will be able to achieve [water quality] standards without evaluating component

[wasteload and load allocations] and how these loads were calculated”). As indicated

earlier, an example of a document that contains the separate TMDLs (in the sense of

numeric amounts) for relevant pollutants, explains the reasoning and calculations

underlying those caps, and allocates those totals among the relevant sources of pollution is

the Bay TMDL.

A TMDL such as the Bay TMDL is neither self-implementing nor directly

enforceable. Rather, it serves as an informational tool that the EPA and the states use in

seeking to achieve the specified pollutant levels – and the applicable water quality

standards – by means of discharge permits and other regulatory tools. See American Farm

Bureau Federation v. EPA, 984 F. Supp. 2d 289, 297-98 (M.D. Pa. 2013), aff’d, 792 F.3d

281 (3d Cir. 2015). To enforce the TMDL limits and corresponding water quality

standards, agencies that issue discharge permits seek to ensure that the total pollution

discharged by point sources does not exceed the wasteload allocations in the relevant

TMDLs. The combined pollution allotted to all of the point sources should equal the sum

of the wasteload allocations in a TMDL. Therefore, the discharge permit for each point

source is to contain water quality based effluent limitations consistent with the

“assumptions and requirements” of the wasteload allocation for that source in any

applicable TMDL. 40 CFR §122.44(d)(1)(vii)(B).

A discharge permit may incorporate provisions related to several TMDLs. The

permits at issue in this case incorporate provisions not only from the Bay TMDL, but also

from TMDLs, developed by the Department and approved by the EPA, for certain

14

waterways.21 Appendices to the Counties’ MS4 permits list the approved TMDLs

applicable to each County. One example, which will be discussed later in this opinion, is

the TMDL for fecal bacteria in Double Pipe Creek, whose watershed spans both Counties.

Chesapeake Bay TMDL and Maryland Watershed Implementation Plan (WIP)

In 2009, after decades of multilateral efforts aimed at restoring the Chesapeake

Bay,22 the EPA began the development of a Chesapeake Bay-wide TMDL.23 After

publishing a draft for a period of public review, the EPA adopted the Bay TMDL in late

2010.24 The Bay TMDL establishes limits for three pollutants – nitrogen, phosphorus, and

sediment – that threaten marine life by feeding large algae blooms that block sunlight and

21

See Maryland Department of the Environment, Approved TMDLs,

https://perma.cc/99S9-C7Q3.

22

For a summary of Bay clean-up efforts over the past several decades, see Farm

Bureau, 984 F. Supp. 2d at 298-303.

23

The EPA “established the Chesapeake Bay TMDL pursuant to a number of

existing authorities, including the [Clean Water Act] and its implementing regulations,

judicial consent decrees requiring EPA to address certain [waters in the Chesapeake Bay

watershed that were failing to meet water quality standards], a settlement agreement

resolving litigation brought by the Chesapeake Bay Foundation, the 2000 Chesapeake

Agreement [between certain Bay states], and Executive Order 13508.” See Bay TMDL at

1-16. That Executive Order directed the EPA to “mak[e] full use of its [Clean Water Act]

authorities to lead a collaborative and effective federal and state effort to meet the Bay’s

nutrient and sediment goals.” Id. at 1-17.

24

See EPA, Clean Water Act Section 303(d): Preliminary Notice of Total Maximum

Daily Load (TMDL) Development for the Chesapeake Bay, 74 Fed. Reg. 47792 (September

17, 2009); EPA, Clean Water Act Section 303(d): Notice for the Establishment of the Total

Maximum Daily Load (TMDL) for the Chesapeake Bay, 76 Fed. Reg. 549 (January 5, 2011)

(stating that the EPA established the Bay TMDL on December 29, 2010).

15

reduce oxygen levels in the water.25 Bay TMDL at 2-6, 2-7. Specifically, the Bay TMDL

pollutant caps are designed to satisfy water quality standards involving “aquatic life uses”

and criteria such as water clarity and dissolved oxygen levels. Id. at 3-1, 3-2.

Given the breadth and complexity of the Bay TMDL, the EPA established a unique

accountability framework to achieve its goals. Bay TMDL at ES-8. Although the Act

generally does not require an implementation plan for a TMDL, the EPA directed each Bay

State to create a “Watershed Implementation Plan” (“WIP”) to reduce pollution to the

levels set by the Bay TMDL. Each Bay State’s WIP serves two basic purposes – to break

down the EPA’s statewide Bay TMDL pollutant allocations among geographic areas and

among point and nonpoint sources within the state, and to identify the programs and

policies that the state will use to achieve those pollutant reductions. The Maryland WIP

was developed by the Department together with the Departments of Planning, Agriculture,

and Natural Resources. Maryland’s Final Phase I Watershed Implementation Plan (Dec.

3, 2010), available at https://perma.cc/8CMV-ENCB (“Maryland WIP”).26 Like the other

25

More precisely, the Bay TMDL divides waterways in the Chesapeake Bay

watershed into 92 “segments,” and establishes individual TMDLs – in the sense of numeric

amounts – for each segment for each of the three pollutants. Thus, the Bay TMDL is “an

assemblage of 276 TMDLs: individual TMDLs for each of the 3 pollutants – nitrogen,

phosphorus, and sediment – for each of the 92 segments (3 x 92 = 276).” Bay TMDL, at

xiii & 2-7.

26

The EPA anticipated that each state would write its WIP in three phases. The

State has published the first two iterations of its WIP and a draft version of the third

iteration. See Maryland Department of the Environment, Watershed Implementation

Plans, https://perma.cc/J985-WQ65. Citations in the text are to the first iteration of the

WIP, often referred to as the Phase I WIP. The “phases” of the WIP should not be confused

16

Bay State WIPs, the Maryland WIP functions as a “roadmap” for how and when the State

will reach the pollution reduction goals set forth in the Bay TMDL. Maryland Department

of the Environment v. Anacostia Riverkeeper, 447 Md. 88, 109 (2016).

Implementing the Maryland WIP in MS4 Permits

The Maryland WIP listed several requirements to be included in the then-upcoming

round of Phase I MS4 permits in Maryland. Two of these requirements correspond to terms

in the Counties’ permits that are part of the dispute in this litigation.

First, a commitment in the Maryland WIP involves restoration of impervious

surfaces – i.e., areas that have been paved or otherwise developed, as opposed to natural,

undeveloped areas. Natural areas allow stormwater to soak into the ground, where

pollutants are filtered to some extent. Impervious surfaces prevent that filtration process.

Instead, stormwater that encounters an impervious surface rushes over it, collecting

pollutants along the way. To “restore” an impervious surface is to make it function more

like a natural terrain that absorbs and filters rain water. Doing so accomplishes the same

end as a direct pollutant control, like a filter or other cleansing mechanism attached to a

conveyance. The less impervious surface that exists, the less polluted stormwater will run

across it and into the conveyances of the MS4. Thus, as is true in general for stormwater

management programs in MS4 permits, an impervious surface restoration requirement

serves as a surrogate for direct pollution controls. See Anacostia Riverkeeper, 447 Md. at

with the two phases of the MS4 permitting program, which will be discussed in some detail

in Part II.D. of this Opinion.

17

122-23. The Maryland WIP called for “[c]ompletion of restoration efforts for twenty

percent of the [Phase I MS4] counties’ impervious surface area that is not already restored

to the maximum extent practicable.” Maryland WIP at 5-30.

Second, another provision of the Maryland WIP refers to many applicable local

TMDLs with stormwater wasteload allocations. For example, for the Counties, the relevant

local TMDLs are compiled, as mentioned above, in appendices to their MS4 permits. The

Maryland WIP requires the creation of “[s]tormwater watershed implementation plans for

each EPA approved stormwater wasteload allocation” in the relevant local TMDLs.

Maryland WIP at 5-30. Such local watershed implementation plans are distinct from the

overall Maryland WIP.

Maryland Stormwater Management Act

In addition to the permitting program, the State Stormwater Management Act has,

since the mid-1980s, required local jurisdictions to implement stormwater management

programs “to reduce as nearly as possible the adverse effects of stormwater runoff.” EN

§4-201. Each county and municipality is to adopt ordinances necessary to implement such

a program consistent with State law. EN §4-202. The Legislature directed the Department

to adopt regulations governing such programs that would, among other things, indicate that

the primary goal is “to maintain after development, as nearly as possible, the

predevelopment runoff characteristics.” EN §4-203(b)(1); see also Anacostia Riverkeeper,

447 Md. at 110-13. The statute authorizes jurisdictions to impose and collect stormwater

remediation fees and other charges to carry out such programs. EN §§4-202.1, 4-204; see

also 96 Opinions of the Attorney General 61 (2011). Such fees provide “important revenue

18

needed to offset the costs of building and maintaining municipal gutters and drains,

monitoring pollution levels, policing illegal discharges of polluted water, and educating the

public on proper environmental practices.” Norfolk Southern, 916 F.3d at 325 (referring

to similar local stormwater fee in Virginia).

The Carroll County and Frederick County MS4 Permits

The Department first issued MS4 permits to Carroll County and Frederick County

during the 1990s as part of Phase I of the MS4 permitting process, and has renewed those

permits several times since then. The permits that are the subject of this case are Carroll

County’s fourth and Frederick County’s third round of MS4 permits, which were both

issued in December 2014. In accordance with State law, the Department first issued draft

permits for public comment. See EN §1-604(a). In each case, the Department held a public

hearing and accepted comments on the draft permit. After considering those comments,

the Department made a Final Determination to issue each permit together with a document

entitled “Basis for Final Determination” that provided an explanation for its action. EN

§1-604(b).

Pertinent to this case, the Maryland WIP commitment involving impervious surface

restoration is incorporated into Part IV.E.2.a of each permit. This provision has two

components. First, it requires each County to submit to the Department an “impervious

surface area assessment” consistent with guidelines provided by the Department. That

assessment, if approved by the Department, “shall serve as the baseline for the restoration

efforts” required by the permit. Second, by the end of the permit term, each County “shall

commence and complete the implementation of restoration efforts for twenty percent of

19

the County’s impervious surface area consistent with the methodology described in [a

Department guidance document] that has not already been restored to the” maximum extent

practicable.

Part IV.E.2.b of each permit includes a provision based on the commitment in the

Maryland WIP concerning local TMDLs. This provision requires each County to submit

to the Department for approval a plan to implement each stormwater wasteload allocation

in each relevant, EPA-approved local TMDL. Each plan must include a final date for

“meeting applicable [wasteload allocations] and a detailed schedule for implementing all

[necessary] structural and nonstructural water quality improvement projects, enhanced

stormwater management programs, and alternative stormwater control initiatives.” Upon

approval by the Department, the plans become enforceable conditions of the permits.

Two other aspects of the permits are at issue here. The first is Part VI.B of each

permit, which requires the Counties to cooperate with other State agencies in the

development of elements of the Counties’ comprehensive growth plans that involve

stormwater management. The second contested aspect of the permits is the absence of an

authorization for “water quality trading.”27 As relevant here, such trading would allow the

Counties to earn credit for pollution reduction by paying others (whether point or nonpoint

sources) to take pollution-reducing actions. A County might consider water quality trading

27

“Water quality trading” is sometimes referred to as “nutrient trading.”

20

in situations where paying another party to achieve a pollution reduction costs less than the

County’s own efforts to achieve a similar reduction.

B. Procedural History

In January 2015, Carroll County sought judicial review of its 2014 MS4 permit in

the Circuit Court for Carroll County. At the request of the parties, the matter was stayed

for more than a year while the parties pursued settlement and while challenges to similar

permits by environmental advocates were being litigated.28 After the stay expired, the

Circuit Court issued an opinion dated June 26, 2017, agreeing with the County on some of

its claims and with the Department on others. The court remanded the County’s permit to

the Department. The Department appealed that ruling and the County filed a cross-appeal.

In January 2015, Frederick County sought judicial review of its 2014 permit in the

Circuit Court for Frederick County. As in the Carroll County case, the matter was stayed

pending settlement discussions and other litigation. After the stay expired, the Circuit

Court issued an opinion dated July 14, 2017, that largely rejected the County’s arguments,

but remanded the permit to the Department to address what the court believed were

ambiguities and inconsistencies in the permit’s wording. Frederick County appealed that

ruling.

The Court of Special Appeals consolidated the two appeals for argument. Prior to

argument and decision in the Court of Special Appeals, the Counties asked this Court to

28

This Court resolved that litigation in Maryland Department of the Environment

v. Anacostia Riverkeeper, 447 Md. 88 (2016).

21

grant a writ of certiorari in their respective cases. The Department agreed that the

Counties’ petitions should be granted. This Court granted the two petitions and

consolidated the cases for argument.

II

Discussion

Both Counties challenge conditions set forth in their most recent MS4 permits,

although some of the bases for their challenges differ.

Two of the alleged flaws in the permits concern the impervious surface restoration

requirement. First, Frederick County argues that the Department exceeded its authority

under the Clean Water Act by failing to consider “practicability” when it included the

impervious surface restoration requirement in its permit. Frederick County bases this

argument on a provision of the Act that requires MS4 permits to include controls to reduce

pollution discharges “to the maximum extent practicable” – what is sometimes called the

MEP standard. Frederick County further argues that, even if the Act allows the Department

to set the restoration requirement without regard to the MEP standard, the Department

arbitrarily and capriciously failed to consider the County’s contention that compliance with

the degree of restoration required by the permit is impossible.

Second, both Counties assert that the Department exceeded its authority under the

Act by including in the permit an impervious surface restoration requirement in which the

baseline for measuring compliance with the requirement relates to the unrestored

impervious surface throughout the entire County, rather than only the area served by the

County’s MS4.

22

Both Counties argue that the Department has unlawfully treated them as Phase I

jurisdictions for purposes of their MS4 permits – thereby subjecting them to more stringent

permit terms required of Phase I jurisdictions than those later required of Phase II

jurisdictions – because it incorrectly classified them in the early 1990s as “medium”

jurisdictions based on population. Carroll County also argues that its inclusion in Phase I

of the MS4 permitting program was arbitrary and capricious.

Both Counties argue that the Department arbitrarily and capriciously failed to

include water quality trading as a compliance mechanism in their permits.

Finally, Carroll County argues that a provision in its permit that requires the County

to cooperate with other State agencies in the development of stormwater-related aspects of

the County’s comprehensive growth plan unlawfully imposes new obligations on the

County.

We first discuss the standards that govern our consideration of these arguments. We

then consider the substantive issues raised by the Counties.

A. What and How We Review

The General Assembly has provided for judicial review of permits issued by the

Department, such as the MS4 permits issued to the Counties. EN §1-601(a)(3), (c). Such

review is based on an administrative record that includes the various items set forth in EN

§1-606(c).29 Judicial review begins in the circuit court pursuant to the Maryland Rules.

29

Among other things, the record may include the permit application and any

accompanying data, documents contained in the supporting file for the draft permit,

comments submitted to the Department from the public, responses to those comments, the

23

See Maryland Rule 7-201 et seq. (governing judicial review of administrative actions when

a statute provides for judicial review).

In an appeal of the circuit court’s review of an agency action, an appellate court

reviews the agency’s action itself rather than the decision of the circuit court.

Hollingsworth v. Severstal Sparrows Point, LLC, 448 Md. 648, 654 (2016). Thus, while

the circuit court decisions here set the stage for our review and determined who would be

appellant and appellee in our Court, we are not assessing the merits of those court decisions.

Rather, we directly review the permits in light of the issues raised by the Counties.

1. Standards for Review of Discharge Permits

a. General Standards for Review of Agency Action

The standards for judicial review of a discharge permit – and their corresponding

levels of deference to the agency – vary depending on whether the court is reviewing an

agency’s fact findings, discretionary decisions, or legal conclusions. See Anacostia

Riverkeeper, 447 Md. at 118-21.

Review of Fact Findings

For fact findings, a reviewing court applies the “substantial evidence” standard,

under which the court defers to the facts found and inferences drawn by the agency when

the record supports those findings and inferences. Anacostia Riverkeeper, 447 Md. at 120.

tape or transcript of any public hearings, and the Department’s statement of the basis for

its determinations with respect to the permit.

24

In particular, with respect to factual issues that involve scientific matters within an

agency’s area of technical expertise, the agency is entitled to “great deference.” Id.

Review of Matters Committed to the Agency’s Discretion

With respect to matters committed to agency discretion, a reviewing court applies

the “arbitrary and capricious” standard of review, which is “extremely deferential” to the

agency. Harvey v. Marshall, 389 Md. 243, 296-99 (2005); Spencer v. Md. State Bd. of

Pharmacy, 380 Md. 515, 529 (2004). This standard is highly contextual, but generally the

question is whether the agency exercised its discretion “unreasonably or without a rational

basis.” Harvey, 389 Md. at 297; Arnold Rochvarg, Maryland Administrative Law, §4.38

at 128 (2011).

For guidance, a reviewing court may look to case law applying the similar standard

in federal administrative law. See Anacostia Riverkeeper, 447 Md. at 120-21; Office of

People’s Counsel v. Public Service Commission, 461 Md. 380, 399 (2018).30 Under this

standard, a reviewing court is not to substitute its own judgment for that of the agency and

should affirm decisions of “less than ideal clarity” so long as the court can reasonably

30

Under the federal standard, the reviewing court may consider whether: (1) the

agency’s choice was rationally connected to the facts found; (2) the agency considered the

relevant factors; (3) the agency made a clear error of judgment; (4) the agency relied on

factors the legislature did not intend for it to consider; (5) the agency failed to consider an

important aspect of the problem; (6) an explanation for the decision runs counter to the

evidence; and (7) the decision is so implausible that it could not be ascribed to a difference

in view or the product of agency expertise. Office of People’s Counsel, 461 Md. at 399

n.16.

25

discern the agency’s reasoning. Bowman Transp., Inc. v. Arkansas-Best Freight System,

Inc., 419 U.S. 281, 285-86 (1974).

Review of the Agency’s Legal Conclusions

With respect to an agency’s legal conclusions, a reviewing court accords the agency

less deference than with respect to fact findings or discretionary decisions. Anacostia

Riverkeeper, 447 Md. at 122. In particular, a court will not uphold an agency action that

is based on an erroneous legal conclusion. Id. However, in construing a law that the agency

has been charged to administer, the reviewing court is to give careful consideration to the

agency’s interpretation.

In construing a statute, a reviewing court applies the oft-stated approach to statutory

construction. That is, the court seeks to ascertain legislative intent – whether that of the

General Assembly or of Congress. That endeavor begins with the plain meaning of the

text, keeping in mind that the plainest language is controlled by the context in which it

appears. Kaczorowski v. Mayor & City Council of Baltimore, 309 Md. 505, 514 (1987).

The legislative history of the statute may then be reviewed to understand the purpose of

the legislation, resolve ambiguities, and confirm the apparent meaning of the text. Past

case law construing a provision is, of course, also helpful. Throughout, the court must be

mindful that the purpose is not to discern “purely judicial notions of public policy,” but

rather legislative intent. BAA, PLC v. Acacia Mutual Life Ins. Co., 400 Md. 136, 157

(2007).

When a party challenges the agency’s interpretation of the statute the agency

administers, the court must assess how much weight to accord that interpretation, keeping

26

in mind that it is “always within [the court’s] prerogative to determine whether an agency’s

conclusions of law are correct.” Schwartz v. Md. Dep’t of Nat. Res., 385 Md. 534, 554

(2005). The weight given an agency’s interpretation of a statute it administers depends on

several factors. Baltimore Gas & Electric Co. v. Public Service Commission, 305 Md. 145,

161 (1986). More weight is appropriate when the interpretation resulted from a process of

“reasoned elaboration” by the agency, when the agency has applied that interpretation

consistently over time, or when the interpretation is the product of contested adversarial

proceedings or formal rule making. Id. at 161-62.

b. Effect of the Clean Water Act’s Scheme of Cooperative Federalism

In our consideration of the Department’s interpretation and application of the Clean

Water Act, we must take into account the extent to which the EPA’s administrative

interpretation and federal case law set parameters for the Department’s actions. The shared

implementation of a federal policy or program by federal and state agencies is sometimes

referred to as “cooperative federalism.” See Anacostia Riverkeeper, 447 Md. at 101. It

can affect how a state court reviews that implementation when the state agency’s actions

are limited by federal policies. In general, a state agency that is delegated the

administration of the discharge permitting program under the Act is “bound to follow

EPA’s interpretation of the [Act].” Natural Resources Defense Council v. New York State

Dep’t of Envtl. Conservation, 34 N.E.3d 782, 794 n.16 (N.Y. 2015) (declining to entertain

27

a challenge to an EPA regulation interpreting the Act and state agency’s compliance with

that interpretation).31

Under the Act’s cooperative federalism scheme, the EPA has delegated the

administration of the Act’s discharge permitting program in Maryland to the Department.

Nonetheless, the EPA reviews and has the right to object to the Department’s draft

discharge permits. 40 CFR §123.44 (“EPA review of and objections to State permits”);

see also Memorandum of Agreement between EPA and Department (May 18, 1989),

available at https://perma.cc/3UNE-4CLN (explaining that the EPA will review all State-

prepared permits and may object to them). In addition, the EPA has overseen Maryland’s

efforts (as well as those of the other Bay States) to achieve the goals of the Bay TMDL –

i.e., efforts to develop and carry out the WIPs. See Farm Bureau, 984 F. Supp. 2d at 323-

24.

31

See also BellSouth Telecommunications, Inc. v. Sanford, 494 F.3d 439, 449 (4th

Cir. 2007) (state’s authority over telecommunications issue is part of deliberately

constructed model of “cooperative federalism” under which state agency applies expertise

and experience “subject to the boundaries set by Congress and federal regulators”); Perry

v. Dowling, 95 F.3d 231, 236-37 (2d Cir. 1996) (a state agency’s interpretation of the

federal Medicaid statute “warrants deference” when “the state has received prior federal-

agency approval to implement its plan, the federal agency expressly concurs in the state’s

interpretation of the statute, and the interpretation is a permissible construction of the

statute”); Aaron Saiger, Chevron and Deference in State Administrative Law, 83 Fordham

L. Rev. 555, 581 (2014) (“State officials who deal with the environment, education, or

antiterrorism are enmeshed in a system of regulatory federalism that often very

substantially deprives them of freedom of action.”).

28

c. Deference Owed to the EPA’s Construction of the Clean Water Act

In assessing the weight to be accorded the EPA’s construction of the Act, we look

to the deference that would be accorded such interpretations under federal case law. In

general, when an agency exercises authority to “make rules carrying the force of law” –

i.e., rulemaking, adjudications, or other actions involving similarly extensive

administrative procedures – the agency’s interpretation warrants deference under Chevron

U.S.A. v. Natural Resources Defense Council, 467 U.S. 837 (1984). Less formal agency

action may also merit Chevron deference depending on “the interstitial nature of the legal

question, the related expertise of the Agency, the importance of the question to

administration of the statute, the complexity of that administration, and the careful

consideration the Agency has given the question over a long period of time.” Barnhart v.

Walton, 535 U.S. 212, 222 (2002).

Under Chevron, a federal court first determines “whether Congress has directly

spoken to the precise question at issue” in the pertinent statute – in this case, the Clean

Water Act. 467 U.S. at 842. If the Congressional intent is clear, the court “must give effect

to [that] unambiguously expressed intent.” Id. at 842-43. But “if the statute is silent or

ambiguous with respect to the specific issue,” the court must decide “whether the [EPA’s]

answer is based on a permissible [or reasonable] construction of the statute.” Id. at 843-

44.

Even if the particular agency interpretation does not meet the criteria for Chevron

deference, a reviewing court may defer to that interpretation based on the persuasiveness

of the agency interpretation, considering factors such as “the thoroughness evident in its

29

consideration, the validity of its reasoning, its consistency with earlier and later

pronouncements, and all those factors which give it power to persuade, if lacking power to

control.” Skidmore v. Swift & Co., 323 U.S. 134, 140 (1944) (Jackson, J.).32

This Court has assessed the validity of State agency actions consistent with a federal

agency’s regulations or interpretations of a federal statute in light of these principles. See

Anacostia Riverkeeper, 447 Md. at 142 & n.61 (citing federal administrative deference case

law and finding an EPA policy memorandum “instructive” on interpretation of federal

regulation under the Clean Water Act); Sugarloaf Citizens’ Ass’n v. Department of the

Environment, 344 Md. 271, 313 (1996) (affirming Department action based in part on EPA

interpretation of the federal Clean Air Act, which was entitled to deference under

Chevron); Koons Ford of Baltimore, Inc. v. Lobach, 398 Md. 38, 54 (2007) (applying

Chevron and adopting the FTC’s interpretation of a federal statute that the FTC

administers); Montgomery Cty. v. Glenmont Hills Associates Privacy World at Glenmont

Metro Ctr., 402 Md. 250, 271-72 (2007) (citing Chevron in adopting HUD’s interpretation

that a federal statute did not preempt local agency action that the Court affirmed).

32

If those factors sound familiar, perhaps it is because Skidmore is a direct ancestor

of the leading case of this Court concerning the degree of judicial deference accorded to

state agency actions. See Baltimore Gas & Electric Co. v. Public Service Commission, 305

Md. 145, 161-62 (1986), citing and relying on Comptroller v. John C. Louis Co., 285 Md.

527, 544 (1978), which cites and relies upon Skidmore.

30

2. Reviewability of Permit Terms Derived from TMDLs and WIP

Incorporation of TMDLs and the Maryland WIP in the Counties’ MS4 Permits

The MS4 permits at issue in this appeal incorporate or reference elements of the Bay

TMDL, the Maryland WIP, and certain local TMDLs. That raises the question whether

this litigation is the appropriate forum for what amounts to a challenge to those prior

administrative actions.

The Appropriate Forum for Challenging Permit Provisions Derived from a TMDL

Carroll County argues that provisions of a TMDL that are implemented in a permit

must be reviewable in the context of judicial review of that permit – i.e., in an action like

this one. The County reasons that, because Maryland statutory law does not provide for

judicial review of State-authored TMDLs and because the TMDLs themselves are not self-

executing, the only viable mode of judicial review is a challenge to a permit.

The County is correct that the Maryland Code does not provide for judicial review

of a TMDL. The County is also correct that a TMDL is not self-executing. Farm Bureau,

792 F.3d at 291 n.4. However, the absence of a statutory mechanism for review of a TMDL

in State court does not mean it is not reviewable in any court. The EPA’s approval of a

state-submitted TMDL “is an act taken pursuant to the [Clean Water Act] and thus is

subject to challenge [in federal court] under the [federal Administrative Procedure Act.]”

Anacostia Riverkeeper, Inc. v. Jackson, 798 F. Supp. 2d 210, 222 (D.D.C. 2011). For

example, the major case challenging the validity of the Bay TMDL was held to be ripe for

judicial review in federal court because the “parties present[ed] a purely legal dispute on a

well-developed record about the EPA’s process of promulgating a TMDL.” Farm Bureau,

31

792 F.3d at 293-94. Similarly, parties challenging other state-prepared, EPA-approved

TMDLs have obtained judicial review of the EPA’s approval of those TMDLs in federal

court. See, e.g., Friends of Earth, Inc. v. EPA, 446 F.3d 140 (D.C. Cir. 2006); Natural

Resources Defense Council v. Muszynski, 268 F.3d 91 (2d Cir. 2001); City of Kennett v.

EPA, 887 F.3d 424 (8th Cir. 2018).

To the extent that the Counties are challenging decisions previously made or actions

taken in adopting an EPA-approved TMDL, judicial review of those decisions or actions

was available in federal court. Unsurprisingly, as this Court has previously indicated, an

action for judicial review of a discharge permit in State court is not the forum for raising

belated challenges to a TMDL that the challenger could have raised elsewhere. See

Anacostia Riverkeeper, 447 Md. at 129 n.46.33 Thus, in an action by a permittee under EN

33

In Anacostia Riverkeeper, this Court cited In re City of Moscow, Idaho, 10 E.A.D.

135, 2001 WL 988721 (EAB July 27, 2001) to illustrate this principle. Moscow was an

opinion of the Environmental Appeals Board (“Board”), the EPA’s final decisionmaker of

administrative appeals under the statutes that the EPA administers. In Moscow, a

municipality pursued an administrative appeal of a discharge permit for its sewage

treatment plant issued by the EPA. The municipality challenged, among other things, a

term in the permit that was derived from a state-prepared TMDL for the water body into

which the plant discharged pollutants. 2001 WL 988721 at *1, *16. The permit term

established a “seasonal constraint” on phosphorus discharges (between May and October,

the “normal growing season months” of algae blooms, which are fed in part by

phosphorus). Id. at *16 n.53.

The municipality argued, among other things, that the EPA’s decision to adopt the

TMDL’s seasonal growth period as part of the permit was arbitrary and capricious, but the

Board disagreed. The Board observed that the TMDL clearly specified the growth period

and that federal regulations required that the municipality’s permit be consistent with the

“assumptions and requirements” of the treatment plant’s wasteload allocation established

by the TMDL. 2001 WL 988721 at *16.

32

§1-601 challenging a permit term derived from a TMDL, the permittee may not base that

challenge on a decision that was previously made in the development of the TMDL.34

Consistent with the principle recognized in Anacostia Riverkeeper, we conclude that

claims concerning a discharge permit that are essentially challenges to a governing TMDL

and that could have been raised in an action for judicial review of the EPA’s approval of

The municipality also claimed that the TMDL’s seasonal growth period was

inaccurate. The Board also rejected that argument, holding that the administrative appeal

of the permit terms was not the appropriate forum for raising that claim. 2001 WL 988721

at *17. The Board reasoned that it was authorized to review “contested permit conditions”

but not the validity of “prior, predicate regulatory decisions that are reviewable in other

fora,” and that the TMDL was a prior predicate regulatory decision reviewable in a federal

district court under the federal Administrative Procedure Act. Id. at *18. The Board

concluded that the municipality’s claim was essentially a belated challenge to

determinations previously made in the TMDL and the EPA’s earlier decision to approve

the TMDL – which were reviewable elsewhere.

As this Court indicated in Anacostia Riverkeeper, that reasoning applies in actions

to review discharge permits in Maryland courts. In Maryland, State courts are authorized

to review a discharge permit issued by the Department, but not a TMDL on which parts of

the permit may be predicated. Specifically, although the General Assembly has provided

for judicial review of discharge permits in EN §1-601(c), it has not authorized judicial

review of State-prepared TMDLs (which are not final until they receive EPA approval).

Instead, as noted in the text, the EPA’s approval of such a TMDL – necessary for it to be

effective – may be challenged in federal court.

34

Of course, just because something is mentioned in a TMDL does not mean that it

would be ripe for a challenge in federal court. For example, when an environmental group

challenged an alleged “authorization” of water quality trading in the Bay TMDL in federal

court, the court held that the claim was not ripe because the Bay TMDL only “expected”

or “encouraged” trading without making a final decision about it – let alone “authorizing”

it in a permit. See Food & Water Watch v. EPA, 5 F. Supp. 3d 62, 73-86 (D.D.C. 2013).

In other words, the challenger failed to identify a final, concrete decision in the TMDL that

was suitable for judicial review. That case illustrates that the principle identified in

Anacostia Riverkeeper applies only to provisions of a TMDL that reflect a reviewable final

action taken in the TMDL.

33

that TMDL cannot be raised in a judicial review action under EN §1-601.35 Accordingly,

as explained further below, we will not entertain some of the Counties’ arguments that are

essentially challenges to provisions in EPA-approved TMDLs.36

B. Whether the Impervious Surface Restoration Permit Term Unlawfully Exceeds

the MEP Standard or is Arbitrary and Capricious

The Clean Water Act, in describing provisions to be included in an MS4 permit,

refers to a standard of “maximum extent practicable” – often denominated by the acronym

“MEP.” 33 U.S.C. §1342(p)(3)(B)(iii). Whether the MEP standard governs all provisions

in an MS4 permit, or only certain provisions, is a matter of debate – a debate that we shall

wade into presently. Frederick County’s flagship argument in its appeal is that the

Department unlawfully disregarded the MEP standard and therefore exceeded its authority

when it included the impervious surface restoration requirement in the County’s permit.

35

We need not, and do not, address whether a State court would have authority to

directly review a TMDL prepared by the Department pursuant to an administrative

mandamus action, Maryland Rule 7-401 et seq., or otherwise.

36

Carroll County argues that the Department is “estopped” from arguing that the

County may not challenge a provision of a TMDL incorporated in its permit. The County’s

basis for this argument is that, in a 2003 case, the Department successfully argued that a

discharger cannot claim to have been aggrieved by a TMDL until the Department proposes

to issue a discharge permit that includes effluent limitations based on the TMDL. See In

re Wicomico River TMDL, No. 22-C-01-000623 (Wicomico Cty. Cir. Ct. June 13, 2003).

The County’s argument is not without some force as the Department’s position here

appears to contradict its argument in Wicomico River. However, the reviewability of a

permit term is a legal question, not subject to an estoppel argument. For the reasons set

forth in the text, it is our view that permit terms that directly implement a decision made in

an EPA-approved TMDL are not subject to review in an action in State court challenging

the permit.

34

The County further argues that, even if the Act allows the Department to include provisions

in the permit without reference to the MEP standard, the impervious surface restoration

requirement is impossible to achieve and that the Department acted arbitrarily and

capriciously in including it in the permit. Carroll County does not join either of these

arguments, although its permit includes an identical impervious surface restoration

requirement.

1. The MEP Standard

Congress did not define the MEP standard in the Act and the EPA has explicitly

declined to define it as well.37 The phrase “maximum extent practicable” suggests a

standard that is, or is close to, the most stringent standard in a hierarchy of possible

standards under the Act. However, in the context of the Act’s standards for pollution

controls, that is not the case.38 To understand why, it is helpful to review the dichotomy

between technology based and water quality based effluent limitations for point sources

and then consider how the MEP standard relates to those limitations.

37

The EPA has explained that it “intentionally [has] not provided a precise

[regulatory] definition of MEP to allow maximum flexibility in MS4 permitting.” EPA,

National Pollutant Discharge Elimination System – Regulations for Revision of Water

Pollution Control Program Addressing Storm Water Discharges, 64 Fed. Reg. 68722,

68754 (December 8, 1999).

38

See Jones Creek Investors, LLC v. Columbia County, Ga., 98 F. Supp.3d 1279,

1300 n.4 (S.D. Ga. 2015) (In the MS4 context, “[t]he phrase ‘maximum extent practicable’

is a term of art, and should not be attributed the ordinary meaning usually applied to those

words.”); National Research Council, Urban Stormwater Management in the United States

(The National Academies Press 2009) at 60 (“[T]he [MEP] standard for MS4s … [is] a

floor, not a ceiling, for permit requirements when receiving waters are impaired.”).

35

The Clean Water Act’s Hierarchy of Pollution Controls

In principle, the most that a regulatory agency can require of a point source is to do

what is necessary to reduce pollutants to a level such that the waterway satisfies water

quality standards. Thus, the most stringent level of control – for any point source – is strict

compliance with water quality standards for the pertinent waterway. Given the difficulty

of calculating and enforcing such standards, Congress in the Act chose not to “make the

perfect the enemy of the good” and authorized the use of technology based effluent

limitations for typical, end-of-pipe point sources. 33 U.S.C. §1311(b)(1)(A). Such

controls achieve some pollution reduction, although often not enough to achieve water

quality standards for the pertinent waterway. As explained above, technology based

effluent limitations are designed from the perspective of the discharger while controls

based on water quality standards – water quality based effluent limitations – are designed

from the perspective of the waterway.

MEP Standard versus Water Quality Based Standard

The MEP standard is analogous to a technology based effluent limitation in that its

reference point is the MS4 operator rather than the waterway.39 A water quality based

effluent limitation is more stringent than an MEP-level control just as such a limitation is

39

National Research Council, supra note 38, at 60 (grouping the MEP standard with

“other technology-based requirements” for stormwater permittees); see also Jones Creek

Investors, 98 F. Supp.3d at 1300 n.4 (MEP standard defined in the pertinent MS4 permits

as “the technology-based discharge standards and controls necessary for the reduction of

pollutants discharged from [an MS4]”).

36

more stringent than a technology based control. Despite this analogy, water quality based

effluent limitations operate differently in end-of-pipe point source permits than they do in

MS4 permits. With an end-of-pipe point source, a technology based effluent limitation is

typically a numeric level of pollution and the point source must install technology to ensure

that the amount of pollution emitted from the pipe is below the specified level. A water

quality based effluent limitation may simply ratchet down that numeric level, requiring the

point source to come up with ways to reduce pollution further.

With MS4s, however, there generally is no corresponding numeric cap on the

amount of pollution discharged by each conveyance within an MS4.40 Instead, the MS4

operator must implement the various MEP-level management programs required by its

permit. In that context, a water quality based control is a program in addition to the MEP-

level programs. To say that water quality based controls are “more stringent” than or

“beyond” MEP-level controls simply means that the MS4 operator must comply with the

water quality based control in addition to the MEP-level controls. For example, Frederick

County’s permit lists six management programs under the MEP standard. See Frederick

County Phase I MS4 Permit MD0068357, Part IV.D.1-6. In addition to those programs,

and under a separate section of the permit, the County is to comply with the impervious

surface restoration requirement. Id., Part IV.E.2.a.

40

See Upper Missouri Waterkeeper v. Montana Dep’t of Envtl. Quality, 438 P.3d

792, 799 (Mont. 2019) (noting that MS4 permits generally have included best management

practices rather than numeric limits).

37

The County and the Department appear to agree that the impervious surface

restoration requirement in the County’s permit is a water quality based control that is in

addition to those provisions included under the MEP standard. However, the County

asserts that the Department may not include such a term in the permit if it “goes beyond”

the MEP standard.

2. Whether an MS4 Permit Term May “Go Beyond” the MEP Standard

At first blush, this Court’s decision in Anacostia Riverkeeper seems to resolve this

issue in the Department’s favor.41 In a background section of that opinion, the Court stated:

MS4s are subject to the MEP standard[.] [They] are not, however,

required to [achieve] effluent limitations necessary to meet water

quality standards. [But the Act] still requires Maryland to set water

quality standards and TMDLs – subject to the EPA’s approval.

Flowing from this obligation is the requirement that MS4s are subject

to effluent limitations that are consistent with [wasteload allocations]

of EPA-approved TMDLs.

41

The Dissenting Opinion of Judge Watts contends that the Court’s holding in

Anacostia Riverkeeper is an “obstacle” to the Department’s position in this case and that

the permit term in question is “incompatible” with Anacostia Riverkeeper. Watts

Dissenting slip op. at 4-5. The Dissenting Opinion appears to have the mistaken belief that

Anacostia Riverkeeper somehow supports Frederick County’s challenge to this permit

term. In fact, in that case, the Court considered a permit term that appears in Phase I MS4

permits of five other jurisdictions and that is identical to the permit term that Frederick

County challenges here. The Court held that the term was valid and authorized by the

Clean Water Act. 447 Md. at 122-26. If we were simply to recite the holding of Anacostia

Riverkeeper and stop, Frederick County loses. But, in fairness to Frederick County and as

indicated in the text, the holding in Anacostia Riverkeeper was in response to a challenge

from a different perspective. Environmental groups argued that the permit term was

inadequate to comply with the MEP standard. Here, Frederick County argues, from the

opposite perspective, that the permit term unlawfully exceeds that standard. However, for

the reasons explicated in the text, we disagree and reach the same outcome that Anacostia

Riverkeeper did – that the permit term is valid and authorized by the Act.

38

447 Md. at 104. In other words, an MS4 permit may include, as needed, effluent limitations

consistent with TMDL wasteload allocations, in compliance with the EPA regulation that

requires a discharge permit for a point source to contain such effluent limitations. See 40

CFR §122.44(d)(1)(vii)(B). Given that the impervious surface restoration requirement is

such an effluent limitation, Anacostia Riverkeeper seems to answer the question raised by

Frederick County – i.e., that the 20 percent impervious surface restoration requirement in

the permit is valid and authorized by the Clean Water Act. However, in Anacostia

Riverkeeper, the Court was addressing a question somewhat distinct from the one posed in

this case. In that case, the question was whether the impervious surface restoration

requirement satisfied the MEP standard whereas in this case the question is whether it

unlawfully exceeds it. The resolution of this question requires statutory construction of the

provision in which the MEP standard appears – 33 U.S.C. §1342(p)(3)(B)(iii) – which we

shall refer to as clause (B)(iii) for ease of reference.

Construing Clause (B)(iii) – Statutory Language

The Clean Water Act specifically addresses municipal and industrial stormwater

discharges in 33 U.S.C. §1342(p), which consists of six paragraphs. Paragraph 3 of that

subsection sets forth “permit requirements.”42 That paragraph reads as follows:

42

Paragraphs 1 and 2 concern the timing of the requirement to obtain certain

stormwater discharge permits. Paragraph 4 concerns the application requirements for those

permits. Paragraph 5 authorizes the EPA to conduct a study on other stormwater discharges

not covered by those permits. Paragraph 6 authorizes the EPA to adopt regulations based

on the study required by paragraph 5. 33 U.S.C. §1342(p)(1)-(2), (4)-(6).

39

(3) Permit requirements

(A) Industrial discharges

Permits for discharges associated with industrial activity shall meet

all applicable provisions of [section 1342] and section 1311 of this

title.

(B) Municipal discharge

Permits for discharges from municipal storm sewers—

(i) may be issued on a system- or jurisdiction-wide basis;

(ii) shall include a requirement to effectively prohibit non-

stormwater discharges into the storm sewers; and

(iii) shall require controls to reduce the discharge of pollutants

to the maximum extent practicable, including management practices,

control techniques and system, design and engineering methods, and

such other provisions as the [EPA] Administrator or the State

determines appropriate for the control of such pollutants.

33 U.S.C. §1342(p)(3). Subparagraph (A) relates to permit requirements for discharges by

industrial sources such as factories, landfills, construction sites, and power plants that have

operations exposed to rain water or snow melt. Subparagraph A does not directly relate to

the requirements in MS4 discharge permits.43

Our focus is on Subparagraph (B) concerning the requirements for MS4 permits.

The first two clauses concern the geographic scope of an MS4 permit (clause (B)(i)) and

43

See 40 CFR §122.26(b)(14) (“Storm water discharge associated with industrial

activity means the discharge from any conveyance that is used for collecting and conveying

storm water and that is directly related to manufacturing, processing or raw materials

storage areas at an industrial plant.”).

40

the separation of stormwater discharges from other discharges (clause (B)(ii)), but do not

include a reference to the MEP standard.

Clause (B)(iii) concerns the controls and provisions required to reduce the discharge

of pollutants from MS4s. As is evident, the MEP standard appears in this clause. The

Department and the County disagree as to the role that the MEP standard plays in clause

(B)(iii).

To construe clause (B)(iii) we begin, of course, with the plain language of the

statute. As this case illustrates, however, statutory language is not always “plain” in the

sense that it may take on different meanings, depending on how one parses a series of

words or clauses. The Department and Frederick County tabulate clause (B)(iii) in slightly

different ways to support their contrary interpretations. We apply an editorial pen below

to illustrate these different interpretations.

Frederick County’s favored construction of clause (B)(iii) can be illustrated as

follows:

Permits for discharges from municipal storm sewers –

(iii) shall require controls to reduce the discharge of pollutants to the

maximum extent practicable, including (1) management practices, (2)

control techniques and systems, (3) design and engineering methods,

and (4) such other provisions as the [EPA] Administrator or the State

determines appropriate for the control of such pollutants.

Under the County’s construction, the “controls” subject to the MEP standard are listed in

a series following the word “including” – a series of four categories that includes (1)

management practices, (2) control techniques and systems, (3) design and engineering

methods, and (4) such other provisions as the permitting agency deems appropriate. In that

41

view, there are four categories of pollution controls that might be required by an MS4

permit, including a final catchall category, and all four fall under the MEP umbrella. As

indicated above, to support its preferred tabulation and avoid a phrase in the middle of the

series of clauses (“system methods”) that the County claims is nonsensical, the County

asserts that the word “system” is the result of a “typographical error” in the statute that

needs to be corrected to “systems.”44

In contrast, the Department’s construction opts for a different tabulation, but does

not require revision of the language of the statute. That interpretation can be illustrated as

follows:

Permits for discharges from municipal storm sewers –

(iii) shall require (1) controls to reduce the discharge of pollutants to

the maximum extent practicable, including (a) management practices,

(b) control techniques and (c) system, design and engineering methods,

and (2) such other provisions as the [EPA] Administrator or the State

determines appropriate for the control of such pollutants.

Under this construction of the statute, the three categories of controls enumerated in the

initial series – i.e., certain “practices,” “techniques,” and “methods” – are subject to the

MEP standard while “other provisions” that the permitting agency deems appropriate under

the final clause are not limited by the MEP standard. The Department’s construction does

not require revision of the text itself, and groups items that could comfortably fit within the

44

In support of its contention that the statute contains a typographical error, the

County notes that the word “systems” appears in various documents related to stormwater

discharge permits, including two statements made while the legislation was debated in

Congress.

42

category of “controls” separately from the final clause’s vaguer and seemingly broader

reference to “appropriate … provisions.”

Confronted with similar competing grammatical arguments concerning the

application of the MEP standard in clause (B)(iii), a state appellate court in California

concluded that “[a]lthough it is not the clearest way of articulating the concept, the

language of [clause (B)(iii)] does communicate the basic principle that the EPA [or an

authorized state] retains the discretion to impose ‘appropriate’ water pollution controls in

addition to those that come within the definition of [MEP].” Bldg. Indus. Assn. of San

Diego Cty. v. State Water Res. Control Bd., 124 Cal. App. 4th 866, 882-83 (2004) (“BIA

case”).45 That court upheld requirements in an MS4 permit based on water quality

standards in the face of a contention, similar to that of Frederick County in this case, that

those provisions unlawfully exceeded the MEP standard.

Thus, the statement in Anacostia Riverkeeper in a somewhat different context and

the assessment of the BIA court in a similar context both favor the Department’s

construction of clause (B)(iii). We also consider what legislative history exists and the

administrative construction of this federal statute by the federal agency charged with

administering it – the EPA.

45

See also John H. Minan, Municipal Separate Storm Sewer System (MS4)

Regulation Under the Federal Clean Water Act: The Role of Water Quality Standards?, 42

San Diego L. Rev. 1215, 1241-42 (2005) (discussion of grammatical argument in BIA case

by law professor who served on the permitting agency in that case).

43

Legislative History of Clause (B)(iii)

When Congress was considering the legislation that added the MS4 permit

requirements to the Act, legislators often spoke in general terms about achieving water

quality standards without elaborating on the MEP standard or addressing whether that

standard should apply to every pollutant control in an MS4 permit. Some statements

suggested that water quality based standards – i.e., standards other than MEP – would be

part of MS4 permits. For example, one senator stated that MS4 permit pollution control

“requirements are to contain control technology or other techniques to control these

discharges and should conform to water quality requirements.” 133 Cong. Rec. S733-02,

1987 WL 928615 (January 14, 1987) (statement of Senator Chafee). On the other hand,

another senator paraphrased clause (B)(iii) in language that mirrors the County’s

interpretation, including substituting the plural “systems” for “system.” Id. (statement of

Senator Durenberger). Yet another member of Congress both alluded to the goal of

controlling stormwater discharges “to protect the quality of the Nation’s waters” and in

paraphrasing the legislation, used the word “systems.” 133 Cong. Rec. H168-03, 1987 WL

928356 (January 8, 1987) (statement of Representative Roe). In the end, what legislative

history exists is “not especially illuminating” on the role of the MEP standard.46

46

Minan, supra, note 45, at 1243-44.

44

EPA’s Administrative Construction of Clause (B)(iii)

The EPA’s position for many years was that an MS4 permit, like any discharge

permit, must achieve compliance with water quality standards.47 Indeed, when it adopted

regulations for Phase I MS4 permits, the agency described the controls that would be

required by such permits as follows: “[MS4] permits are to establish controls to the

maximum extent practicable[,] effectively prohibit non-storm water discharges to the

[MS4] and, where necessary, contain applicable water quality-based controls.” EPA,

National Pollutant Discharge Elimination System Permit Application Regulations for

Storm Water Discharges – Final Rule, 55 Fed. Reg. 47990, 47995 (November 16, 1990)

(“EPA Preamble to 1990 Phase I MS4 Rule”) (emphasis added).

The EPA partially backed away from this view after the United States Court of

Appeals for the Ninth Circuit held that MS4 permits need not include water quality based

effluent limitations. See EPA, National Pollutant Discharge Elimination System –

Regulations for the Water Pollution Control Program Addressing Storm Water Discharges

- Final Rule, 64 Fed. Reg. 68722, 68753 (December 8, 1999) (“EPA Preamble to 1999

47

EPA, Interim Permitting Approach for Water Quality-Based Effluent Limitations

in Storm Water Permits, 61 Fed. Reg. 43761 (August 26, 1996); EPA, Questions and

Answers Regarding Implementation of an Interim Permitting Approach for Water Quality-

Based Effluent Limitations in Storm Water Permits, 61 Fed. Reg. 57425 (November 6,

1996); EPA, Memorandum from E. Donald Elliott, Assistant Administrator and General

Counsel, EPA, re: Compliance with Water Quality Standards in NPDES Permits Issued to

Municipal Separate Storm Sewer Systems (January 9, 1991) at 1; see also Oliver A. Houck,

TMDLs III: A New Framework for the Clean Water Act’s Ambient Standards Program, 28

Envtl. L. Rep. 10415, 10428 (1998) (discussing the EPA’s interpretation); Minan, supra,

note 45, at 1245-46 (same).

45

Phase II MS4 Rule”) (recognizing that a Ninth Circuit decision “disagree[d] with EPA’s

interpretation of the relationship between” §1311 and §1342(p)). Specifically, in

Defenders of Wildlife v. Browner, 191 F.3d 1159, 1164 (9th Cir. 1999), the Ninth Circuit

held that §1342(p)(3) “unambiguously demonstrates that Congress did not require [MS4s]

to comply strictly with” §1311(b)(1)(C), which requires that discharge permits contain

water quality based effluent limitations as needed.48 On the other hand, the court also stated

that the final provision of clause (B)(iii) gives the EPA (and thus a state permitting agency)

the discretion to “determine that ensuring strict compliance with state water-quality

standards is necessary to control pollutants [or] to require less than strict compliance with

state water quality standards.” 191 F.3d at 1166.49 Thus, while the Ninth Circuit did not

48

As noted earlier, while clause (A) of §1342(p)(3) requires industrial stormwater

dischargers to comply with all of §1311 (i.e., with both technology based and water quality

based effluent limitations), clause (B) lays out different requirements for MS4s without

mentioning §1311. The Ninth Circuit reasoned that, for MS4 permits, clause (B)(iii)

“replaces” both the technology and water quality based effluent limitation requirements in

§1311. 191 F.3d at 1165.

49

A related question – which is not raised here and which, therefore, we do not

address – is whether MS4 permits may require strict compliance with water quality

standards. That question is at issue in two cases in the United States Court of Appeals for

the District of Columbia Circuit that are currently in settlement proceedings. Center for

Regulatory Reasonableness v. EPA, Case Nos. 17-1060 & 16-1246 (D.C. Cir.). The

challengers in those cases argue that certain Phase II MS4 general permits issued by the

EPA violate clause (B)(iii) by requiring compliance with water quality standards. The

situation here is different in that no party claims that the Counties’ permits expressly

require compliance with water quality standards.

46

agree with the EPA’s existing construction, it nevertheless recognized that a permitting

agency had discretion to include permit terms based on water quality standards.50

In any event, after the Defenders of Wildlife decision, the EPA modified its

administrative interpretation of clause (B)(iii). Whereas the agency had taken the view that

MS4 permits, like all discharge permits, must contain water quality based effluent

limitations as needed, after the Ninth Circuit decision the EPA viewed such limitations as

permissible, but not mandatory, in MS4 permits. It cited Defenders of Wildlife as support

for the proposition that clause (B)(iii) “specifically preserves the authority for EPA or

[authorized states] to include other provisions determined appropriate to reduce pollutants

in order to protect water quality.” EPA Preamble to 1999 Phase II MS4 Rule, 64 Fed. Reg.

at 68788. Accordingly, the Phase II regulation provides that “[a]s appropriate, the permit

[for a small MS4] will include [m]ore stringent terms and conditions, including permit

requirements ... based on an approved [TMDL] or equivalent analysis, or where the [EPA

or state] determines such terms and conditions are needed to protect water quality.” 40

CFR §122.34(c)(1). Although the 1999 preamble and rule concern Phase II MS4 permits,

the EPA’s views on water quality based limitations generally apply to all MS4 permits.

50

Other courts have pointed to Defenders of Wildlife as setting forth the discretion

that the EPA (and state permitting agencies) have in drafting MS4 permit terms to require

pollution controls that satisfy the MEP standard or a more demanding water quality based

standard. See Natural Resources Defense Council v. New York State Dep’t Envtl

Conservation, 994 N.Y.S. 2d 125, 135 (N.Y. App. 2014), aff’d, 34 N.E.3d 782 (N.Y. 2015);

Conservation Law Foundation, Inc. v. Boston Water and Sewer Commission, 2010 WL

5349854 at *5-6 (D. Mass. 2010); Tualatin Riverkeepers v. Oregon Dep’t Envtl Quality,

230 P.3d 559, 563-64 & n.10 (Ore. App. 2010); City of Arcadia v. State Water Resources

Control Board, 135 Cal.App. 4th 1392, 1429 (2006).

47

For example, the Defenders of Wildlife decision upheld Phase I MS4 permits issued by the

EPA that included water quality based limitations.51

The EPA has maintained that position through at least the time period relevant for

this litigation. In other words, since 1990, the EPA has held the view that the Act at least

authorizes water quality based effluent limitations in MS4 permits. 52 For example, in a

letter to the Department concerning Frederick County’s permit that appears in the

administrative record, the EPA made clear that permitting agencies may include water

quality based effluent limitations in MS4 permits: “Where the [permitting] authority

determines that MS4 discharges have the reasonable potential to cause or contribute to a

water quality standard excursion as [the Department] has done in this case, EPA

recommends that the … permitting authority exercise its discretion to include appropriate

narrative and/or numeric water quality-based effluent limitations … as necessary to meet

water quality standards.” EPA Letter to Maryland Department of the Environment re

51

See In re: Arizona Municipal Storm Water NPDES Permits for City of Tucson,

Pima County, City of Phoenix, City of Mesa, and City of Tempe, 1998 WL 284966, at *2

n.1 (EAB May 21, 1998) (stating, in the administrative decision that was reviewed in

Defenders of Wildlife, that the permittees were properly classified as operators of MS4s

requiring Phase I permits).

52

In its critique of the impervious surface restoration term of the Frederick County

MS4 permit, the Dissenting Opinion of Judge Watts discounts the EPA’s interpretation of

the Clean Water Act which, as indicated in the text, follows the interpretation of the Act

by the Ninth Circuit in Defenders of Wildlife. See Watts Dissenting slip op. at 11-12 &

n.7. Given the ambiguity in clause (B)(iii), the EPA’s interpretation – which is consistent

with the construction of the statute by the federal courts – is entitled to deference under

Chevron (and even if the Chevron did not apply, under Skidmore).

48

Supplemental Comments on Frederick County Phase I MS4 Permit (September 23, 2014).

The EPA also stated that the requirement of consistency between TMDLs and permits

applies to MS4s as it does to all point sources: “Pursuant to 40 CFR 122.44(d)(1)(vii)(B),

where there is an applicable [TMDL] approved or established by EPA, a [discharge] permit

must include effluent limitations that are consistent with the wasteload allocation . . . in the

TMDL. This includes MS4 permits.” Id.

Harmonizing MS4 Permit Terms with the TMDL Process

Clause (B)(iii) is to be read harmoniously with the Act as a whole, including the

TMDL process. See King v. St. Vincent’s Hospital, 502 U.S. 215, 221 n.10 (1991) (when

construing statute, court should read statute as a whole and harmonize its provisions);

Condon v. State of Maryland-Univ. of Maryland, 332 Md. 481, 491 (1993) (same). In our

view, the EPA’s and Department’s interpretation of clause (B)(iii) is more consistent with

the Act as a whole than the alternative proposed by Frederick County.

The EPA’s regulations require that a water quality based effluent limitation be

derived from the applicable water quality standard, without referring to a practicability test.

Permitting agencies “shall ensure that [t]he level of water quality to be achieved by [water

quality based effluent limitations] on point sources ... is derived from, and complies with,

all applicable water quality standards.” 40 CFR §122.44(d)(1)(vii)(A). The EPA’s

rationale is that “[d]eriving water quality-based effluent limits from water quality standards

is the only reliable method for developing water quality-based effluent limits that protect

aquatic life and human health.” EPA, National Pollutant Discharge Elimination System;

Surface Water Toxics Control Program – Final Rule, 54 Fed. Reg. 23868, 23879 (June 2,

49

1989) (preamble to publication of the EPA’s rule that, in part, adopted 40 CFR

§122.44(d)(1)(vii)). Importantly, this rationale does not distinguish between types of point

sources, i.e., whether the discharger is a factory, a wastewater treatment plant, an MS4, or

any other kind of point source. The process of implementing TMDLs via discharge permits

“results in effluent limits that protect aquatic life and human health because the limits are

derived from water quality standards.” Id. In other words, when translating TMDL

wasteload allocations to effluent limitations in a permit, the pertinent water quality standard

remains the touchstone. Thus, when an entity discharges to a waterway subject to a TMDL,

its permit must contain effluent limitations consistent with the “assumptions and

requirements” of the corresponding wasteload allocation in the TMDL. 40 CFR

§122.44(d)(1)(vii)(B).

When the final provision of clause (B)(iii) is read to encompass water quality based

effluent limitations, MS4 permits are treated like any other discharge permit for purposes

of implementing TMDLs. This interpretation harmonizes clause (B)(iii) with the TMDL

provisions insofar as the latter likewise do not distinguish between types of point sources.

By contrast, if permitting agencies must constrain all TMDL based effluent limitations in

MS4 permits by some sort of practicability analysis, there would be tension with the basic

tenet that water quality based effluent limitations must derive from water quality standards.

Summary

In including the impervious surface restoration requirement in Frederick County’s

permit, the Department acted consistently with the EPA’s interpretation of clause (B)(iii)

– that is, that the Act authorizes permitting agencies to include water quality based effluent

50

limitations in MS4 permits without reference to the MEP standard. As explained earlier,

clause (B)(iii) is ambiguous. A federal court reviewing the EPA’s interpretation of an

ambiguous federal statutory provision under Chevron would defer to the agency’s

reasonable construction of that language. In our view, the EPA’s interpretation of clause

(B)(iii) is a reasonable construction that is consistent with the rest of the Act and accords

with the Ninth Circuit decision in Defenders of Wildlife and other applicable court

decisions. Even under the less deferential Skidmore standard of review, a federal court

would likely defer to the agency’s interpretation in light of its consistent view that MS4

permits are subject to standards emanating from TMDLs. Moreover, the Department was

“bound to follow EPA’s interpretation” in light of the Clean Water Act’s scheme of

cooperative federalism. Natural Resources Defense Council v. New York State Dep’t of

Envtl Conservation, supra. Accordingly, we hold that the Department did not act

unlawfully in including a water quality based effluent limitation (the impervious surface

restoration requirement) not subject to the MEP standard in the County’s permit.53

3. Whether the Inclusion of the Impervious Surface Restoration Requirement

in Frederick County’s Permit was Arbitrary and Capricious

Frederick County also argues that, regardless of whether the Act authorizes the

Department to include an impervious surface restoration requirement in MS4 permits

53

Because we hold that the Act authorizes the impervious surface restoration

requirement in the County’s permit, we need not address the Department’s alternative

argument that Maryland law allows such a condition as consistent with the federal Act’s

provision allowing for more stringent state-set permit conditions. See 33 U.S.C. §1370.

51

without reference to the MEP standard, the Department acted arbitrarily and capriciously

when it included such a provision in the County’s permit. The County notes that, during

the comment period on the draft permit, it submitted to the Department a report that

purportedly demonstrated that compliance with the permit’s requirements within five years

was financially and logistically impossible.54

As noted earlier, when agency action is challenged as arbitrary and capricious, the

question is whether there was a rational basis for that action. See Part II.A. of this Opinion.

In answering that question, a reviewing court is to be “extremely deferential” to the agency

and not to substitute its own judgment for that of the agency. To assess whether the

Department acted arbitrarily and capriciously in its consideration of Frederick County’s

objection to the permit term, we review both the procedure that the Department followed

and the substance of its action.

Procedure

Consistent with EN §1-604(a), the Department first issued a “tentative

determination” together with the draft permit on June 28, 2014. A public comment period

followed, during which the Department received many comments on the draft permit.

After consideration of those comments, the Department published a “final determination”

54

As described above, the General Assembly authorized counties to charge a

stormwater remediation fee to help finance stormwater management and restoration

required by MS4 permits. See EN §4-202.1. Frederick County adopted a fee of 1¢; at oral

argument before this Court, the County explained that it had elected to use general funds

to finance its obligations under the Clean Water Act.

52

on December 10, 2014, along with the final permit, consistent with EN §1-604(b). See

Basis for Final Determination to Issue Frederick County’s NPDES MS4 Permit

MD0068357 (December 2014) (“Basis for Final Determination – Frederick County”).

In general, the Environment Article gives the Department broad discretion in

replying to comments when the agency takes final action on a proposed permit. The

Department is not obliged to respond to all public comments, but rather may “pick and

choose” the comments it addresses. Kor-Ko Ltd. v. Maryland Dep’t of the Env’t, 451 Md.

401, 422 n.18 (2017). The fact that an agency does not change a proposed action or

regulation in light of comments requesting a change does not mean that the process lacked

a meaningful opportunity for comment or that the agency failed to consider those

comments. See Fogle v. H & G Rest., Inc., 337 Md. 441, 463 (1995).

Substance

In its comments on the draft permit, Frederick County voiced its concerns about the

feasibility of compliance with the impervious surface restoration requirement. The

Department addressed Frederick County’s concerns about cost and feasibility, as well as a

number of other issues in the Basis for Final Determination that the Department published

with the final version of the permit.55 Basis for Final Determination – Frederick County at

18. The Department noted that the County believed that the 20 percent restoration

55

In the same document, the Department also addressed similar cost and feasibility

“estimates” submitted by Charles County and Harford County. Basis for Final

Determination – Frederick County at 18.

53

requirement “exceeds an MEP level of effort and that compliance would be financially and

operationally infeasible.” Id. at 22. The Department responded to those concerns by

explaining that the restoration requirement was necessary for consistency with the Bay

TMDL and the Maryland WIP. Id. The Department also stated that the EPA had reviewed

the permit for such consistency and was “satisfied” that the permit achieved it based, in

part, on the impervious surface restoration requirement. Id. Although the Department’s

response may not have amounted to a point-by-point refutation of every detail of the

County’s comments, it did address the significant issues raised by the County. We cannot

say that the Department failed to respond in a reasoned manner.

In particular, the Department had a rational basis for saying that the restoration

requirement is necessary for consistency with the Bay TMDL and the Maryland WIP. As

this Court recognized in Anacostia Riverkeeper, the EPA relied on the Maryland WIP,

which included the impervious surface restoration requirement, when developing the Bay

TMDL and the restoration requirement was a “key element” in securing EPA’s

endorsement of the Maryland WIP. 447 Md. at 128.

It was reasonable for the Department to respond to the County’s claim of

impossibility by explaining that the restoration requirement derives from the Bay TMDL

and the Maryland WIP. The Bay TMDL and Maryland WIP were the result of significant

deliberation among various stakeholders together with the EPA and the Department. For

example, the record shows that Frederick County and the Department had been discussing

practicability and feasibility since at least 2012.

54

In our view, the Department was not arbitrary or capricious in including the

impervious surface restoration requirement in Frederick County’s MS4 permit.

C. Whether the Permits Exceed the Appropriate Geographic Scope of an MS4 Permit

Both Counties assert that their permits exceed the appropriate scope of an MS4

permit. The Counties focus on Part IV.E. of their permits. That section of the permit

requires the County to (1) conduct a detailed watershed assessment for the entire County;

(2) complete restoration of 20 percent of the impervious surface area in the County; (3)

develop and implement restoration plans for meeting applicable stormwater wasteload

allocations in EPA-approved TMDLs; (4) conduct public outreach and encourage public

participation in the watershed assessments, restoration plans, and achievement of the

TMDL limits and water quality standards; and (5) evaluate and document its progress in

meeting stormwater wasteload allocations in EPA-approved TMDLs.

The Counties argue that the Department exceeded its authority under the Clean

Water Act in its specification of the impervious surface restoration condition and in

requiring compliance with stormwater wasteload allocations in applicable EPA-approved

TMDLs. To some extent, these arguments are based on making a distinction between the

permittee – in these cases, Frederick and Carroll Counties – and the activity that is

authorized by the permits – the discharge of pollutants by the MS4s operated in each

County.

1. Jurisdiction-Wide versus System-Wide Permits

The Clean Water Act provides that “[p]ermits for discharges from municipal storm

sewers may be issued on a system- or jurisdiction-wide basis.” 33 U.S.C.

55

§1342(p)(3)(B)(i). The EPA’s regulations reiterate that a permitting authority such as the

EPA or the Department may issue permits for Phase I MS4s on a system-wide or

jurisdiction-wide basis. See 40 CFR §122.26(a)(1)(v) (in exercising residual designation

authority to require Phase I permit, state or EPA may make designation on system-wide or

jurisdiction-wide basis), 40 CFR §122.26(a)(3)(ii) (permit for a large or medium MS4 may

be issued on system-wide basis or on a number of other bases, including with reference to

the “jurisdiction”). Neither the statute nor the regulations elaborate on what it means for

an MS4 permit to be issued on a “jurisdiction-wide” basis – as opposed to a “system-wide”

basis.56 The explanation offered by the EPA at the time it adopted these regulations

indicates that it was concerned with ensuring that permitting authorities had the necessary

flexibility to adapt permits to local conditions such as existing administrative systems,

police powers, and land use authority. EPA Preamble to 1990 Phase I MS4 Rule, 55 Fed.

Reg. at 48043.

56

The EPA regulations suggest that – at least with respect to a Phase I MS4 that is

classified as “large” or “medium” – a “jurisdiction-wide” permit may cover only a portion

of the corresponding system. See 40 CFR §122.26(a)(3)(ii) (authorizing the issuance of

either a system-wide permit “covering all discharges from [the MS4]” or “distinct permits

for appropriate categories of discharges within [the MS4] including, but not limited to …

discharges located within the same jurisdiction…”) (emphasis added). This provision does

not concern residually designated Phase I MS4s.

56

The permits that are the subject of this appeal are each issued to a County – a

jurisdiction – in its capacity as the operator of an MS4 – a system.57 But the challenges

raised by the Counties cannot be resolved by the descriptive label attached to their MS4

permits. The Counties contend that, regardless of whether a permit is issued on a system-

wide or jurisdiction-wide basis, the scope of the regulatory conditions in the permit must

relate to the discharges authorized by the permit. They argue that the baseline calculation

for the impervious surface restoration requirement effectively makes the Counties

responsible for pollutants carried by stormwater that does not flow into their MS4s. The

Counties further argue that permit provisions related to stormwater wasteload allocations

in local TMDLs also do so.

2. The Impervious Surface Restoration Requirement

Impervious surface restoration requirements have been part of MS4 permits issued

by the Department since at least 1999. Maryland WIP at 2-26. The previous generation

of each County’s permit included an impervious surface restoration requirement of 10

percent of each County’s unrestored impervious surface.58

57

The Carroll County permit also includes, as co-permittees, all of the incorporated

municipalities in the County and thus pertains to several jurisdictions and several systems.

See 40 CFR §122.26(a)(3), (b)(1).

58

The general permit applicable to Phase II small MS4s also includes an impervious

surface restoration term, although it differs from the one included in the permits of Phase

I MS4s like the Counties. The current Phase II general permit requires restoration of 20

percent of the unrestored impervious surface in each permittee’s urbanized area by 2025.

57

The Impervious Surface Restoration Condition in the Current Permit

With respect to impervious surface restoration, the current permit provides:

Within one year of permit issuance, [the] County shall submit an

impervious surface area assessment consistent with the methods

described in the [Department] document “Accounting for Stormwater

Wasteload Allocations and Impervious Acres Treated, Guidance for

National Pollutant Discharge Elimination System Stormwater Permits”

(MDE, June 2011 or subsequent versions). Upon approval by [the

Department], this impervious surface area assessment shall serve as the

baseline for the restoration efforts required in this permit.

By the end of this permit term, [the] County shall commence and

complete the implementation of restoration efforts for twenty percent

of the County’s impervious surface area consistent with the

methodology described in the [Department] document cited in [this

section] that has not already been restored to the MEP. Equivalent

acres restored of impervious surfaces, through new retrofits or the

retrofit of pre-2002 structural [best management practices], shall be

based upon the treatment of the WQv criteria and associated list of

practices defined in the 2000 Maryland Stormwater Design Manual.

For alternate [best management practices], the basis for calculation of

equivalent impervious acres restored is based upon the pollutant loads

from forested cover.

Carroll County Phase I MS4 Permit MD0068331, Part IV.E.2.a; Frederick County Phase I

MS4 Permit MD0068357, Part IV.E.2.a.

On its face, this provision does not require the County to undertake impervious

surface restoration outside the geographic area that drains to the MS4, as it does not dictate

where such restoration must take place.59 But the permit provision uses unrestored

59

Some permit terms specify actions within the MS4 service area. For example,

Part IV.D. of the permit requires the County to implement certain management programs

in “areas served by [the] County’s MS4.” Some required programs involve actions that

are necessarily conducted on a county-wide basis, including outside the service area of the

MS4 – e.g., an “acceptable stormwater management program” under EN §4-201 et seq., an

58

impervious surface throughout the entire County – not just within the MS4 service area –

as a starting point, or baseline, for calculating the required restoration.60 (In the case of

both Counties, the County’s MS4 serves only a portion of the County’s geographic area).

The Counties do not contend that the inclusion of an impervious surface restoration

requirement itself is beyond the scope of an MS4 permit. Rather, they argue that the

reference to a county-wide measure of impervious surface as the baseline for the

requirement in the permit exceeds the Department’s authority. They assert that the

reference to that baseline in a permit has the effect of making the County responsible for

pollutants that never enter the County’s MS4.

Anacostia Riverkeeper

This Court considered the validity of an impervious surface restoration requirement

in Anacostia Riverkeeper. In that case, the Phase I MS4 permits in question included an

identical term requiring the permittee counties to restore 20 percent of the unrestored

“acceptable erosion and sediment control program” under EN §4-101 et seq. and a “public

education and outreach program to reduce stormwater pollutants.” MS4 Permits, Part

IV.D. 1, 2, 6. If the permits are modified (as sought by the Counties) to allow water quality

trading as a compliance method, the pollution reductions for which a County would receive

credit would not necessarily occur within the County, much less within its MS4 service

area. See Part II.E. of this Opinion.

60

In particular, the permit term refers to restoration of 20 percent of the County’s

impervious surface area consistent with the methodology in the Department’s guidance

document. That methodology involves a calculation of the impervious surface area

throughout the entire County (after excluding certain areas that are not directly at issue

here). See Accounting for Stormwater Wasteload Allocations and Impervious Acres

Treated (August 2014) at 1, 6-10.

59

impervious surface over the five-year period covered by their permits. The requirement

was challenged by environmental advocacy groups as “too opaque” to satisfy the Act’s

direction that MS4 permits include provisions to reduce pollutants that satisfy the MEP

standard.61 They also argued that the Department had failed to adequately explain its use

of the 20 percent restoration condition or how that level of restoration would achieve the

Bay TMDL.

This Court concluded that impervious surface restoration, as carried out in

accordance with the Department’s Stormwater Design Manual (incorporated by reference

in the permit term), is a stormwater management practice that functions as a “surrogate”

for direct reduction of pollutants in stormwater and that satisfies the MEP standard. 447

Md. at 122-23. Noting that the 20 percent restoration requirement was consistent with the

Maryland WIP, the Court further held that the Department’s decision to include that

requirement in the permits under review was supported by substantial evidence and was

not arbitrary and capricious. Id. at 128-29. The Court also upheld the temporal baseline

selected by the Department for measuring compliance with the 20 percent requirement. In

particular, it held that the Department had not erred in using the measure of unrestored

impervious surface in the counties in 2002 as the baseline. Id. at 132.

In this case, the Counties also challenge the baseline used for the impervious surface

restoration requirement. However, in contrast to Anacostia Riverkeeper, the basis of that

61

The MEP standard is discussed in Part II.B. of this Opinion.

60

challenge is geographic rather than temporal.62 It is rooted in the notion that MS4 permits

under the Act regulate discharges of pollutants only from an MS4 itself. See 33 U.S.C.

§1342(p)(3) (setting forth permit requirements for “permits for discharges from [MS4s]”).

In the Counties’ view, use of a county-wide baseline violates that principle because some

of the impervious surface included in that baseline is associated with pollution that never

enters the MS4.63 According to the Counties, to be consistent with the Clean Water Act,

an impervious surface restoration requirement must reference a baseline that includes only

the MS4 service area.64

62

The Counties point out that the use of 2002 as the baseline year for assessment of

the County’s impervious surface – instead of 1985, the baseline year in the Maryland WIP

– would effectively increase the target amount of restoration. Use of 2002 as the baseline

year would increase the baseline amount of impervious surface by including development

between 1985 and 2002. (In Anacostia Riverkeeper, environmental groups had argued that

a baseline year later than 2002 should have been used – i.e., that use of the 2002 baseline

was too lenient). However, in arguing that they are being held responsible for pollutant

discharges that do not emanate from their MS4s, the Counties focus on the geographical

element of the baseline calculation.

63

This is based on the following reasoning. Obviously, rain can fall anywhere in a

jurisdiction, such as a county, that operates an MS4. The rain will carry some pollutants

into conveyances within the county’s MS4 and, from there, into waterways. Other

pollutants, however, may never encounter the MS4. Instead, they will run into waterways

directly from fields, farms, parking lots, or other land uses in the county that are out of

reach of the MS4. Under the Act, the pollutants carried through the MS4 constitute a form

of point source pollution, and the pollutants not carried through the system are a form of

nonpoint source pollution (often called “stormwater runoff”). Since MS4 permits under

the Act authorize only discharges from point sources, such a permit may only include

conditions related to stormwater and the accompanying pollutants that enter (and are

discharged from) the MS4, not stormwater that never encounters the MS4. See Envtl Def.

Ctr., Inc. v. EPA, 344 F.3d 832, 841 n.8 (9th Cir. 2003).

64

Carroll County also invokes the doctrine of offensive non-mutual collateral

estoppel to argue that the Department is barred from using a county-wide baseline for

61

Origin of the 20 Percent Restoration Requirement

There is no question that the pollutant discharges that the permit authorizes are those

from each County’s MS4. As this Court noted in Anacostia Riverkeeper and as discussed

in the previous section of this Opinion, the impervious surface restoration term is a water

quality based effluent limitation authorized by 33 U.S.C. §1342(p)(3)(B)(iii). In particular,

such a permit term is a numeric water quality based effluent limitation, as recognized by

the EPA.65

impervious surface. In particular, the County cites a 2003 administrative decision by the

Department’s final decisionmaker, which struck certain provisions of wastewater discharge

permits issued to three poultry processors. Tyson Foods, Inc., et al. v. MDE, OAH Case

No. MDE-WMA-063-200200001 (June 12, 2003). The final decisionmaker concluded

that, under State law, the permits could not include conditions that required the processors

to undertake certain activities relating to chicken manure at the farms of those who raised

chickens that were sold or otherwise provided to the processors, particularly when the

growers were not co-permittees.

The Tyson Foods administrative decision did not involve an MS4 permit, much less

an issue identical to the one in this case, and did not discuss the Clean Water Act, EPA

regulations, or any other federal law, for that matter. Under those circumstances, the

doctrine of offensive non-mutual collateral estoppel does not apply to determine the

outcome of this case. See Garrity v. Maryland State Board of Plumbing, 447 Md. 359, 369

(2016) (among other things, issue decided in prior adjudication must be identical for

collateral estoppel to apply). The reasoning of the administrative decision in Tyson Foods

may be analogous in some respects to the argument advanced by the Counties in this case,

but it is not dispositive.

65

See EPA, Post-Construction Performance Standards & Water Quality-Based

Requirements: A Compendium of Permitting Approaches (June 2014) at 19 (including

impervious surface restoration terms in Maryland MS4 permits in a list of examples of

numeric water quality based effluent limitations); EPA, Revisions to the November 22,

2002 Memorandum “Establishing Total Maximum Daily Load (TMDL) Wasteload

Allocations (WLAs) for Storm Water Sources and NPDES Permit Requirements Based on

WLAs” (November 26, 2014) at 10 (identifying an identical 20% restoration term in the

Prince George’s County MS4 permit as a numeric water quality based effluent limitation).

62

Importantly, the amount of impervious surface to be restored is simply a surrogate

or proxy for an amount of pollution to be reduced. The Department’s guidance document

incorporated in the permit term explains how to calculate loads of pollution reduced, given

a certain kind and quantity of impervious surface restoration activity. Thus, when the

Department is determining how a county should calculate the number of impervious

surface acres to be restored, the Department is effectively determining a measure of

pollution reduction.

As explained earlier, the EPA’s regulations require that a water quality based

effluent limitation be derived from applicable water quality standards, without reference to

a practicability test. See 40 CFR §122.44(d)(1)(vii)(A). This is because “[d]eriving water

quality-based effluent limits from water quality standards is the only reliable method for

developing water quality-based effluent limits that protect aquatic life and human health.”

EPA, National Pollution Discharge Elimination System: Surface Water Toxics Control

Program – Final Rule, 54 Fed. Reg. 23868, 23879 (June 2, 1989); see also Natural

Resources Defense Council v. Fox, 909 F. Supp. 153, 156 (S.D.N.Y. 1995).

With respect to the baseline for the impervious surface restoration requirement,

those regulations require a permitting agency to craft the numeric component of a water

quality based effluent limitation by reference to “all applicable water quality standards.”

40 CFR §122.44(d)(1)(vii)(A). Thus, when establishing how each County is to calculate

the number of impervious surface acres to be restored – i.e., the proxy for an amount of

pollution to be reduced – the Act and EPA regulations direct the Department to focus on

what is necessary to achieve water quality standards in the Bay and the waters that feed it.

63

In our view, the Department’s use of a county-wide baseline as a reference point for

calculating the impervious surface restoration condition does not exceed the Department’s

authority under the Act because the impervious surface restoration condition implements a

stormwater wasteload allocation in a TMDL (specifically, the Bay TMDL) designed to

achieve water quality standards. Since at least 1991 the EPA has determined in various

contexts, including regulation, that permitting authorities may make trade-offs between

pollutant allocations for point and nonpoint sources. The EPA’s definition of TMDL

contemplates such trade-offs. See 40 CFR §130.2(i) (“If … nonpoint source pollution

controls make more stringent load allocations practicable, then wasteload allocations can

be made less stringent. Thus, the TMDL process provides for nonpoint source control

tradeoffs.”).

Given that the possibility of such trade-offs is inherent in the definition of TMDL,

it is perhaps not surprising that the EPA has reiterated that concept when discussing how

states are to develop TMDLs. See EPA, Surface Water Toxics Control Program and Water

Quality Planning and Management Program, 57 Fed. Reg. 33040, 33048 (July 24, 1992)

(“States have the flexibility to consider the relative costs of point and nonpoint source

controls when preparing TMDLs, along with such other factors as reliability, relative

effectiveness, and degree of assurance that nonpoint source controls will actually be

implemented and maintained.”); EPA, Guidance for Water Quality-based Decisions: The

TMDL Process (1991) at 15 (“Under the [Act], the only federally enforceable controls are

those for point sources through the NPDES permitting process. In order to allocate loads

among both nonpoint and point sources, there must be reasonable assurances that nonpoint

64

source reduction will in fact be achieved. Where there are not reasonable assurances, under

the [Act], the entire load reduction must be assigned to point sources.”).

This long-established EPA policy is a reasonable interpretation of the Act and is

entitled to deference under Chevron. Even if the EPA policy were not entitled to Chevron

deference under federal law, we would defer to the agency under Skidmore and our own

standards of review. As explained at the outset of this opinion, the Act requires the

establishment of TMDLs when an existing regime of point source pollution controls is

inadequate to achieve water quality standards. TMDLs reflect pollutant levels necessary

to achieve those standards in compliance with the Act. The EPA has reasonably concluded

that permitting authorities must have the discretion to allocate pollutant loads between

point and nonpoint sources as needed to achieve the TMDL limits, including potentially

ratcheting up the requirements on point sources when necessary. See Farm Bureau, 984

F. Supp.2d at 326 (in a case concerning the Bay TMDL, describing how a permit writer

may apportion pollutant amounts – “loads” – among point and nonpoint sources in

accordance with EPA guidance).66

66

In practice, the broad discretion to allocate TMDL-established pollutant amounts

between point and nonpoint sources means that permitting agencies may impose a level of

pollution reduction on point sources in part to help offset nonpoint source pollution. See

Michael M. Wenig, How “Total” Are “Total Maximum Daily Loads”? – Legal Issues

Regarding the Scope of Watershed-Based Pollution Control Under the Clean Water Act,

12 Tul. Envtl. L.J. 87, 117 & n.131 (1998) (recognizing that TMDL allocations can require

point sources to “bear the brunt of pollution reductions necessary to achieve” TMDLs);

Oliver A. Houck, TMDLs III: A New Framework for the Clean Water Act’s Ambient

Standards Program, 28 ELR 10415, 10420 (August 1998) (recognizing permitting

agencies’ option of “ratcheting down further on point sources” when setting wasteload

allocations).

65

Thus, nonpoint source pollution reduction may be assigned to point sources – i.e.,

through wasteload allocations in the development of TMDLs. At bottom, it is this

assignment of pollutant reductions to their wasteload allocations that is the essence of the

Counties’ objection to the impervious surface restoration requirement in their permits.67

The Department’s use of a county-wide baseline for the impervious surface restoration

condition is thus related to the broad discretion of the states and the EPA, in drafting a

TMDL, to assign an amount of nonpoint source pollution reduction to point sources.

Moreover, federal regulations require that point source permits contain effluent

limitations consistent with the “assumptions and requirements” in wasteload allocations in

applicable TMDLs. See 40 CFR §122.44(d)(1)(vii)(B). As this Court noted in Anacostia

Riverkeeper, this standard is flexible. 447 Md. at 135. In this case, the impervious surface

restoration term in the Counties’ permits is consistent with the underlying premise of the

Bay TMDL (by way of the Maryland WIP) that Maryland’s Phase I MS4 permits will

include a corresponding impervious surface restoration requirement.

That provision underwent significant development before reaching its final form in

the permits. For example, in accordance with the EPA regulations governing discharge

permits and a related memorandum of understanding with the Department, the EPA

67

The Maryland WIP states that the impervious surface restoration “strategy” (i.e.,

30% cumulative restoration for Phase I MS4s) is associated with a particular “load

reduction,” i.e., a certain quantity of pollution reduction. Maryland WIP at 5-30.

66

formally objected to the Counties’ draft permits because, among other things, the

impervious surface restoration requirement was “not adequately expressed” and did not

achieve compliance with the Bay TMDL. See EPA, Specific Objection to Carroll County

Phase I MS4 Permit MD0068331 (September 20, 2012); EPA, Specific Objection to

Frederick County Phase I MS4 Permit MD0068357 (September 20, 2012). In response to

such objections and to comply with the requirement of consistency between TMDLs and

discharge permits, the Department adjusted the impervious surface term in the Counties’

permits to a form acceptable to the EPA. The EPA found the consistency requirement to

be satisfied in the final version of the permits and withdrew its objection. EPA,

Supplemental Comments on Carroll County Phase I MS4 Permit (September 23, 2014);

EPA, Supplemental Comments on Frederick County Phase I MS4 Permit (September 23,

2014).

Summary

The impervious surface restoration term in the Counties’ MS4 permits is a numeric

water quality based effluent limitation corresponding to Maryland’s stormwater wasteload

allocation within the Bay TMDL. As such, when crafting that limitation, the Department

was authorized to focus on what would be necessary to achieve water quality standards,

and the Department determined that the baseline calculation method it chose was necessary

to achieve applicable water quality standards for the Bay. The Department did not exceed

67

its authority under the Clean Water Act when it directed calculation of the impervious

surface using a county-wide baseline.68

3. Restoration Requirement Related to Local TMDLs

Both Counties point to certain permit conditions that require the Counties to adopt

restoration plans and provide reports concerning compliance with stormwater wasteload

allocations set forth in EPA-approved TMDLs for waterways in the Counties. They argue

that these provisions unlawfully make the Counties responsible for discharges of third

parties. These provisions appear in Part IV.E. of each County’s permit and read as follows:

2. Restoration Plans

* * *

b. Within one year of permit issuance, [the] County shall submit to [the

Department] for approval a restoration plan for each stormwater

[wasteload allocation] approved by EPA prior to the effective date of

the permit. The County shall submit restoration plans for subsequent

TMDL [wasteload allocations] within one year of EPA approval. Upon

approval by [the Department], these restoration plans shall be

enforceable under this permit. As part of the restoration plans, [the]

County shall:

i. Include the final date for meeting applicable [wasteload allocations]

and a detailed schedule for implementing all structural and

nonstructural water quality improvement projects, enhanced

stormwater management programs, and alternative stormwater control

initiatives necessary for meeting applicable [wasteload allocations];

ii. Provide detailed cost estimates for individual projects, programs,

controls, and plan implementation;

68

Given this conclusion, we need not address whether the impervious surface

restoration requirement is permissible as a State-determined effluent limitation that is

“more stringent” than what the Act requires.

68

iii. Evaluate and track the implementation of restoration plans through

monitoring or modeling to document the progress toward meeting

established benchmarks, deadlines, and stormwater [wasteload

allocations]; and

iv. Develop an ongoing, iterative process that continuously implements

structural and nonstructural restoration projects, program

enhancements, new and additional programs, and alternative [best

management practices] where EPA approved TMDL stormwater

[wasteload allocations] are not being met according to the benchmarks

and deadlines established as part of the County’s watershed

assessments.

* * *

4. TMDL Compliance

[The] County shall evaluate and document its progress toward meeting

all applicable stormwater [wasteload allocations] included in EPA

approved TMDLs. An annual TMDL assessment report with tables

shall be submitted to [the Department]. This assessment shall include

complete descriptions of the analytical methodology used to evaluate

the effectiveness of the County’s restoration plans and how these plans

are working toward achieving compliance with EPA approved TMDLs.

[The] County shall further provide:

a. Estimated net change in pollutant load reductions from all completed

structural and nonstructural water quality improvement projects,

enhanced stormwater management programs, and alternative

stormwater control initiatives;

b. A comparison of the net change in pollutant load reductions detailed

above with the established benchmarks, deadlines, and applicable

stormwater [wasteload allocations];

c. Itemized costs for completed projects, programs, and initiatives to meet

established pollutant reduction benchmarks and deadlines;

d. Cost estimates for completing all projects, programs, and alternatives

necessary for meeting applicable stormwater [wasteload allocations];

and

69

e. A description of a plan for implementing additional watershed

restoration actions that can be enforced when benchmarks, deadlines,

and applicable stormwater [wasteload allocations] are not being met or

when projected funding is inadequate.

Carroll County Phase I MS4 Permit MD0068331, Part IV.E.2.b, IV.E.4; Frederick County

Phase I MS4 Permit MD0068357, Part IV.E.2.b, IV.E.4.

The Counties assert that these permit terms are overbroad because some EPA-

approved local TMDLs assign nonpoint source pollution to the Counties’ MS4s, which are

point sources. Carroll County specifically cites the fecal bacteria TMDL for Double Pipe

Creek – one of the EPA-approved local TMDLs incorporated by reference in Attachment

B to the Carroll County permit.69

The Double Pipe Creek TMDL assigns certain nonpoint source pollution – namely,

“contributions [of fecal bacteria] from domestic animal and [septic system] sources” – to a

stormwater wasteload allocation, which includes pollution budgeted to Carroll County’s

MS4.70 Because the permit requires the County to develop “restoration plans” to achieve

the stormwater wasteload allocations of relevant local TMDLs, the County argues that the

permit makes the County responsible for addressing nonpoint pollution from third parties

that never enters the County’s MS4. The County uses the Double Pipe Creek TMDL as an

69

The Double Pipe Creek watershed includes parts of both Counties and is also

incorporated in Frederick County’s permit.

70

The Double Pipe Creek TMDL distributes this nonpoint source pollution between

Carroll County’s and Frederick County’s MS4s.

70

example, but this argument would apply to any EPA-approved local TMDL that assigns

nonpoint source pollution to stormwater wasteload allocations.71

This dispute concerns not so much the incorporation of EPA-approved local TMDLs

in the permit, as the decisions that were made in the development of those TMDLs. In the

case of the Double Pipe Creek TMDL, Carroll County is questioning a decision made when

the EPA approved the Double Pipe Creek TMDL – namely, the decision to allocate

pollution from nonpoint sources to the Counties’ MS4s by way of a stormwater wasteload

allocation in the TMDL.

Frederick County argues that, like the impervious surface restoration term, the

restoration planning requirement “unlawfully regulates stormwater beyond the scope” of

the Department’s authority. The County bases this argument on the assertion that the local

TMDLs “cover[] areas that do not drain to the County’s MS4.” The County provides little

explanation for this argument, but as far as we can tell, it derives from the same concern

raised by Carroll County – i.e., the decision made by the Department at the local TMDL

development stage to include nonpoint source pollution within the stormwater wasteload

allocation.

71

This issue is somewhat distinct from the issue discussed in the previous section

of this Opinion concerning impervious surface restoration in that the allocations at issue

there derived from the EPA’s reliance on the Maryland WIP in devising the Bay TMDL,

rather than directly from the EPA-approved TMDL itself.

71

For the reasons outlined earlier in this Opinion,72 the Counties should have raised

these arguments in a challenge to the EPA’s approval of the Double Pipe Creek TMDL and

other, similar local TMDLs. See, e.g., City of Kennett v. EPA, 887 F.3d 424 (8th Cir. 2018)

(municipal challenge to EPA-approved TMDL that would affect municipality’s wastewater

permit). Therefore, we will not entertain these arguments here. See Anacostia Riverkeeper,

447 Md. at 129 n.46.

D. Whether the Counties are Appropriately Classified as Phase I Jurisdictions

Frederick County first received an MS4 permit as a Phase I jurisdiction in 1994. It

subsequently applied for and received a Phase I permit in 2002. In 2006, it applied for the

Phase I permit at issue in this appeal. It first contested its status as a Phase I jurisdiction

during the public comment period following the Department’s publication of its draft

permit in 2014 and reiterated those arguments when it sought judicial review of the final

2014 permit.

Carroll County first received an MS4 permit as a Phase I jurisdiction in 1995. It

subsequently applied for and received Phase I permits in 2000 and 2005. Unlike Frederick

County, it did not question its status as a Phase I jurisdiction during the administrative

process for its most recent permit, which was issued in 2014, but first contested its status

as a Phase I jurisdiction when it sought judicial review of that permit.73

72

See Part II.A.2 of this Opinion.

73

The Department argues that Carroll County may not now challenge its Phase I

classification because, unlike Frederick County, it failed to raise the issue during the public

comment period on its draft 2014 permit. However, given that Frederick County did

72

Both Counties argue that the Department has unlawfully treated them as Phase I

jurisdictions because it has incorrectly classified them as “medium” (and therefore Phase

I) – as opposed to “small” (and therefore Phase II) – MS4 jurisdictions since the time when

they first applied for and received their first MS4 permits in the early 1990s. This

distinction matters because, as indicated earlier, Phase I jurisdictions have generally been

subject to earlier and more stringent permit requirements than Phase II jurisdictions. In

particular, the Counties point to the impervious surface restoration requirement in their

Phase I permits.74 As relief, both Counties seek to be re-classified as Phase II jurisdictions

with their permit terms conformed to those that apply to Phase II MS4s.

1. Application of the MS4 Permit Requirement in Phases

Phase I MS4 Permits

In 1987, when Congress added the permit requirement for MS4s to the Clean Water

Act, it did not require permits for all MS4 discharges immediately. Instead, it adopted a

staggered approach.75 This approach started with applying the permit requirement first to

challenge the classification during the administrative process for its permit and that the

issue is essentially the same for both Counties, we will not avoid the issue on the basis of

lack of preservation.

74

The impervious surface restoration requirement is more stringent in Phase I MS4

permits than a similar term in Phase II MS4 permits, in three ways: larger baseline (county

wide vs. urbanized areas), earlier deadline (2019 vs. 2025), and higher percentage of area

to be restored (30% vs. 20%).

75

Congress created this staggered approach in the Water Quality Act of 1987 by

explicitly recognizing that all MS4 discharges were subject to the Act’s permit

requirement, establishing a moratorium on that requirement until 1994, and then exempting

73

discharges from systems with the greatest potential to pollute waterways, which was

referred to as Phase I. These MS4s included those serving larger populations, because

areas with larger and denser populations tend to have more developed land with impervious

surface and, as a result, generate more stormwater pollution.76 Also included in the first

round were MS4s determined by the EPA or a state to be significant contributors of

pollutants, regardless of the size of the population served by those MS4s. This statutory

authority to issue permits based on water quality impact (as opposed to the proxy of

population served) is often referred to as the “residual designation authority” of the EPA

and the states.

For our purposes, the relevant Phase I categories77 are the following:

(1) Large MS4. A discharge from an MS4 serving a population of

250,000 or more, referred to in the statute as a “large MS4.” 33

U.S.C. §1342(p)(2)(C), (p)(4)(A).

(2) Medium MS4. A discharge from an MS4 serving a population of

100,000 or more but less than 250,000, referred to in the EPA’s

certain discharges from that moratorium at various intervals. See 33 U.S.C. §1342(p)(1)-

(2). As a result, the permit requirement was imposed on MS4s in stages.

76

Population served as a proxy for the amount of pollution in stormwater because

“discharges from [MS4s] serving larger populations are thought to present a higher

potential for contributing to adverse water quality impacts.... [P]ollutant loads from urban

runoff strongly depend on the total area and imperviousness of developed land, which in

turn is related to population.” EPA Preamble to 1990 Phase I MS4 Rule, 55 Fed. Reg. at

48038.

77

In all, Phase I covered five categories of MS4 stormwater discharges. See 33

U.S.C. §1342(p)(1)-(2). The other two Phase I categories are discharges for which a permit

had been issued before 1987 and discharges associated with industrial activity – neither of

which is at issue in this appeal. 33 U.S.C. §1342(p)(2)(A)-(B).

74

regulations as a “medium MS4.” 33 U.S.C. §1342(p)(2)(D); 40

CFR §122.26(a)(1)(iv).

(3) Residually Designated MS4. A discharge for which the EPA or a

state “determines that the stormwater discharge contributes to a

violation of a water quality standard or is a significant contributor

of pollutants to waters of the United States.” 33 U.S.C.

§1342(p)(2)(E).

The EPA adopted regulations in 1990 setting forth the permit requirements for Phase I

jurisdictions. EPA, National Pollutant Discharge Elimination System Permit Application

Regulations for Storm Water Discharges – Final Rule, 55 Fed. Reg. 47990 (November 16,

1990), codified in 40 CFR §122. Other than establishing different deadlines for the

submission of permit applications by large and medium jurisdictions, the regulations

generally did not distinguish among these three categories of Phase I MS4s. See 40 CFR

§122.26(d).

Thus, in the early 1990s, an MS4 operated by a local government, like those of the

Counties, would be required to obtain a Phase I permit if: (1) the MS4 served 100,000 or

more people based on census figures, or (2) the EPA or the state had classified the MS4 as

a Phase I jurisdiction under the residual designation authority.

Phase II MS4 Permits

The Phase II round of MS4 permits covered stormwater discharges other than the

Phase I categories. 33 U.S.C. §1342(p)(6). Included in Phase II are MS4s serving fewer

than 100,000 people, referred to as “small” MS4s. In 1999, the EPA adopted regulations

setting forth permit requirements for small MS4s. See EPA Preamble to 1999 Phase II

75

MS4 Rule; see also 40 CFR §122.34.78 Those regulations provided deadlines for initial

Phase II permit applications at various intervals during the early 2000s.

2. Population Classification for Purposes of Phase I

As noted above, the Clean Water Act classifies MS4s according to the population

served by the MS4. The statute does not define what it means for an MS4 to “serve” a

population of a given size. In carrying out its statutory charge to adopt regulations on MS4

permit requirements,79 the EPA defined “medium” MS4s as falling into one of four

subcategories. The most relevant here included systems comprising storm sewers that are:

(i) Located in an incorporated place with a population of 100,000 or

more but less than 250,000, as determined by the latest Decennial

Census by the Bureau of the Census (appendix G); or

(ii) Located in the counties listed in appendix I, except municipal

separate storm sewers that are located in the incorporated places,

townships or towns within such counties;

40 CFR §122.26(b)(7)(i)-(ii) (as adopted in 1990). Like the statute, the regulations on their

face appear to use as a reference point the total population of the particular jurisdiction

without attempting to refine that number according to the portion of the population that

lives or works within the area “served” by the MS4.

78

For reasons not relevant here, the 1999 small MS4 regulations were remanded

and reissued in 2016. See Envtl. Def. Ctr., Inc. v. EPA, 344 F.3d 832 (9th Cir. 2003)

(remanding the 1999 regulations); EPA, National Pollutant Discharge Elimination System

(NPDES) Municipal Separate Storm Sewer System General Permit Remand Rule, 81 Fed.

Reg. 89320 (December 9, 2016).

79

33 U.S.C. §1342(p)(4).

76

Appendix I, referenced in the second subcategory of the regulation, listed 32

counties and was entitled “Counties With Unincorporated Urbanized Areas Greater Than

100,000, But Less Than 250,000 According to the Latest Decennial Census by the Bureau

of the Census” (emphasis added). As is evident, the title of Appendix I refers not only to

“unincorporated” areas, but also to “urbanized” areas – a term that does not appear in the

statute or otherwise in the EPA’s regulations.

In explanatory material that accompanied the 1990 publication of the Phase I

regulations – what is sometimes referred to informally as a “preamble” to such a

publication80 – the agency elaborated on its conception of the second subcategory. It stated

that the second subcategory was meant to capture MS4s in “counties having areas that are

designated as urbanized areas by the latest decennial Bureau of Census estimates and where

the population of such areas exceeds 100,000 [but is less than 250,000], after the population

in the incorporated places, townships or towns within such counties is excluded.” EPA

Preamble to 1990 Phase I MS4 Rule, 55 Fed. Reg. at 48039.81 As defined by the Census

Bureau, the term “urbanized” generally refers to “high density development.” Id. at 48041

n.5.

80

See note 17 above.

81

An EPA guidance document issued shortly after adoption of the Phase I

regulations similarly stated the “medium” MS4 category included “Counties with census

designated urbanized areas that have a population greater than [or] equal to 100,000 but

less than 250,000 after incorporated areas, towns, and townships within such counties are

excluded.” EPA, Guidance Manual for the Preparation of Part 1 of MS4 Permit

Applications (April 1991) at 9 (emphasis added).

77

In its initial iteration in connection with the regulations adopted in 1990, Appendix

I listed jurisdictions in the second subcategory based on figures from the 1980 census – at

that time “the latest decennial census” – as did Appendix G with respect to jurisdictions in

the first subcategory. In 1999, at the same time that the EPA adopted regulations governing

Phase II MS4 permits, the agency also updated Appendix I (as well as Appendix G) based

on the 1990 census – which was then “the latest decennial census.” But the EPA also

amended the regulation concerning “medium” population jurisdictions to refer specifically

to the 1990 census and deleted the reference to the “latest” census. The agency stated that

it would not continue to update those appendices based on later decennial censuses. In the

preamble to the publication of those regulations and amendments, the EPA explained that

it was “freezing” the regulatory definition and listing based on the 1990 census because all

the covered MS4s had already applied for permits and “the deadlines from the existing

regulations have lapsed.”82 EPA Preamble to 1999 Phase II MS4 Rule, 64 Fed. Reg. at

68838, 68848-49. The EPA further explained that MS4s that later met the definition of a

“medium” jurisdiction could be made subject to the Phase I requirements by the permitting

agency, alluding to the agency’s residual designation authority under the Act. Id. at 68749

(“the permitting authority can always require more from operators of MS4s serving ‘newly

over 100,000’ populations”); see also EPA, National Pollutant Discharge Elimination

82

As noted earlier, at that time, Carroll and Frederick Counties were among those

operators of MS4s that, at the behest of the Department, had already applied for, and

received, Phase I permits, although they were not listed in Appendix I.

78

System – Proposed Regulations for Revision of the Water Pollution Control Program

Addressing Storm Water Discharges, 63 Fed. Reg. 1536-01, 1567 (January 9, 1998).

3. Residu

This text is long and has been trimmed here. Open the source document for the complete record.