In the Matter of the Petition of Blue Water Balt., et al., Nos. 1426 & 1803, September 

Term, 2022. Opinion by Nazarian, J.

ENVIRONMENTAL LAW – PERMITS AND CERTIFICATIONS – DISCHARGE 

OF POLLUTANTS

The Department of the Environment is afforded wide flexibility in choosing municipal 

separate storm sewer system (“MS4”) permit terms that comply with the federal maximum 

extent practicable (“MEP”) standard. The Department has discretion to include water 

quality-based effluent conditions in addition to the MEP standard to protect water quality

and has broad discretion in how it achieves consistency with wasteload allocations 

(“WLAs”). The Department did not act arbitrarily or capriciously in issuing MS4 permits

with terms it found consistent with applicable total maximum daily load WLAs to protect 

water quality. The administrative record reveals a rational basis for and substantial 

evidence to support the Department’s decision to include the challenged permit 

requirements. 
Circuit Court for Baltimore City 

Case No. 24-C-21-005448 

Circuit Court for Baltimore County 

Case No. C-03-CV-21-004013 

REPORTED 

IN THE APPELLATE COURT 

OF MARYLAND 

______________________________________ 

CONSOLIDATED CASES 

______________________________________ 

Nos. 1426, 1803 

September Term, 2022 

______________________________________ 

IN THE MATTER OF THE PETITION OF 

BLUE WATER BALTIMORE, INC., ET AL.

______________________________________ 

 Wells, C.J., 

 Nazarian, 

 Tang, 

 

JJ. 

______________________________________ 

Opinion by Nazarian, J. 

______________________________________ 

 Filed: January 31, 2024 
In this appeal, environmental advocates challenge the most recent stormwater 

permits issued by the Maryland Department of the Environment (the “Department”) to 

Baltimore City and Baltimore County. They argue that the permits don’t do enough to limit 

pollution or flooding, are legally deficient, and require a do-over. In these consolidated 

cases initiated in the Circuit Courts for Baltimore County and Baltimore City, Blue Water 

Baltimore, Inc., the Chesapeake Bay Foundation, Inc., and various individuals (the 

“Environmental Advocates”) assert that (1) the municipal separate storm sewer system 

(“MS4”) permits fail to meet water quality standards of receiving waters, (2) the permits 

violate the anti-backsliding provision of the Clean Water Act, and (3) the Department 

otherwise failed to “consider the totality of information available, resulting in 

disproportionate impacts.” The Department and City of Baltimore defended the permits 

and both circuit courts affirmed the final determination of the Department to issue them. 

We affirm as well. 

I. BACKGROUND1

A. General Overview Of Discharge Permit Requirements.

MS4 permits are a type of National Pollutant Discharge Elimination System 

1 MS4 permitting has been explained in depth already in connection with other 

challenges to other MS4 permits and we need not reinvent that wheel here. See 

Maryland Dep’t of the Env’t v. Anacostia Riverkeeper, 447 Md. 88 (2016); Maryland 

Dep’t of the Env’t v. Cnty. Comm’rs of Carroll Cnty., 465 Md. 169 (2019); Maryland 

Small MS4 Coal. v. Md. Dep’t of the Env’t, 479 Md. 1 (2022). For much more extensive 

legal, historical, and scientific background on MS4 permitting, see Anacostia 

Riverkeeper, 447 Md. at 96–103, and Carroll County, 465 Md. at 182–97, and for 

extensive background on the Chesapeake Bay Total Maximum Daily Load and the 

Clean Water Act, see American Farm Bureau Fed’n v. EPA, 984 F. Supp. 2d 289, 294–

307 (M.D. Pa. 2013). 
2

(“NPDES”) permit, 33 U.S.C. §§ 1311(a), 1342, and in Maryland, the Department is the 

NPDES permitting authority, as delegated by the Environmental Protection Agency 

(“EPA”). 33 U.S.C. § 1342(a)(5), (b); Md. Code (1987, 2014 Repl. Vol., 2022 Supp.), 

§ 9-253 of the Environment Article (“EN”); COMAR 26.08.04.01. Under the Clean Water 

Act, all point source2 discharges of pollutants are prohibited unless authorized by permit. 

33 U.S.C. § 1311(a). 

Generally, discharge permits must include: “(1) effluent limitations that reflect the 

pollution reduction achievable by using technologically practicable controls and (2) any 

more stringent pollutant release limitations necessary for the waterway receiving the 

pollutant to meet ‘water quality standards.’” Piney Run Pres. Ass’n v. Cnty. Comm’rs of 

Carroll Cnty., 268 F.3d 255, 265 (4th Cir. 2001) (quoting American Paper Inst. v. EPA, 

996 F.2d 346, 349 (D.C. Cir. 1993)). In other words, “[e]ffluent limitations may be 

[(1)] ‘technology based’ or [(2)] ‘water quality based.’” Carroll County, 465 Md. at 186; 

see also 33 U.S.C. § 1362(11) (defining “effluent limitation” as “any restriction . . . on 

quantities, rates, and concentrations of chemical, physical, biological, and other 

constituents which are discharged from point sources into navigable waters”). Those are 

2 A point source is “any discernible, confined and discrete conveyance,” and includes, 

for example, “any pipe, ditch, channel, tunnel, . . . or vessel or other floating craft, from 

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

“nonpoint source” is “[u]ndefined by the statute,” but “includes dispersed runoff from 

rainwater or snowmelt that sweeps over buildings, farms, and roadways, and that carries 

pollutants and pesticides into navigable waters, their tributaries, and groundwater.” 

Maryland Small MS4 Coal., 479 Md. at 7.
3

not necessarily “mutually exclusive goals” and certain permit requirements can support 

both. Maryland Small MS4 Coal., 479 Md. at 42.

Typical “end-of-pipe” discharges from factories or wastewater treatment plants use 

technology-based effluent limitations, which are “designed from the perspective of the 

discharger” and specify “a numeric level of pollution . . . . [T]he point source must install 

technology to ensure that the amount of pollution emitted from the pipe is below the 

specified level.” Carroll County, 465 Md. at 211–12. “If technology based limitations do 

not achieve the water quality standards, permits may include ‘any more stringent limitation 

. . . necessary to meet water quality standards’—i.e., ‘water quality based effluent 

limitations.’” Id. at 187 (quoting 33 U.S.C. § 1311(b)(1)(C); 40 C.F.R. § 130.7(c)). 

B. MS4 Permit Requirements.

This appeal involves a specific kind of discharge system: stormwater pollutants that 

pass through municipal separate storm sewer systems, known colloquially as MS4s. MS4s 

include complex systems of drains, gutters, ditches, and outfalls that dispose of untreated 

rain and runoff and “[t]he quantity of stormwater that flows through these conveyances 

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

land . . . , and other activities on the land . . . .” Id. at 188–89. MS4s are unpredictable, so 

the statute distinguishes them from the typical “end-of-pipe” permit standards. “It is also 

difficult to discern the amount of pollutant that any one discharger contributes to a 

waterbody because municipalities have so many outfalls, or discharge points, leading into 

the waters.” Anacostia Riverkeeper, 447 Md. at 98. The Baltimore County and Baltimore 

City MS4 systems in particular carry water from large land masses, including impervious 
4

(i.e., paved over) developed areas, that picks up various pollutants as it flows downstream 

and eventually into the Chesapeake Bay.

As a result, MS4 permits must be “more comprehensive than the typical NPDES 

permit,” Maryland Small MS4 Coal., 479 Md. at 11, and they involve management 

programs rather than numeric caps on the amount of pollutants discharged. These programs 

include features the Department describes as “things like erosion and sediment control, 

litter-reduction, and stormwater management—designed to reduce the amount of pollution 

that makes it into the stormwater in the first place.” The programs are considered best 

management practices (“BMPs”), and they can be “an appropriate control when ‘[n]umeric 

effluent limitations are infeasible.’” Anacostia Riverkeeper, 447 Md. at 99 (quoting 40 

C.F.R. § 122.44(k)(3)). 

1. The MS4 technology-based standard is the MEP standard.

The Clean Water Act carved out a different standard for MS4s, distinct from 

numeric caps on discharges typically required for NPDES point sources. Id. at 98 

(“Congress adopted a flexible approach to the control of pollutants in MS4s.”). MS4 

permits instead require controls of stormwater point sources “to reduce the discharge of 

pollutants to the maximum extent practicable,” 33 U.S.C. § 1342(p)(3)(B)(iii),3 a principle 

3 The full text of 33 U.S.C § 1342(p)(3)(B) provides:

(B) 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 nonContinued . . . 
5

commonly referred to as the “MEP 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,” and its differences from typical point source regulation reflect the 

unique and complicated nature of MS4s as pollution sources. Carroll County, 465 Md. at 

212; see also id. at 234–37 (discussing how the MEP standard is more flexible and allows 

for pollution mitigation programs that serve as surrogates for typical NPDES 

requirements). “Congress did not define the MEP standard in the Act and the EPA has 

explicitly declined to define it as well.” Id. at 210. The MEP standard is, however, less 

stringent than water quality based effluent limitations. Id. at 211–12. “[T]his approach 

contemplates that states shall set controls they deem necessary to reduce the discharge of 

pollutants into their waters.” Anacostia Riverkeeper, 447 Md. at 178 (citing 33 U.S.C. 

§ 1342(p)(3)(B)(iii)). And this leaves broad discretion in the Department to establish and 

define programs for MS4s.

2. MS4 water quality based effluent limitations are discretionary, 

but if used, must be consistent with total maximum daily load 

(“TMDL”) wasteload allocations (“WLAs”).

Discharge permits also must achieve limitations “necessary to meet water quality 

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 Administrator or the State determines appropriate for 

the control of such pollutants.
6

standards,”4 as required by 33 U.S.C. § 1311(b)(1)(C). But again, MS4s are different—the 

overarching MEP approach assigned to MS4s “unambiguously demonstrates that Congress 

did not require municipal storm-sewer discharges to comply strictly with 33 U.S.C. 

§ 1311(b)(1)(C).” Defenders of Wildlife v. Browner, 191 F.3d 1159, 1164 (9th Cir. 1999). 

MS4s “are not . . . required to impose effluent limitations necessary to meet water quality 

standards,” Anacostia Riverkeeper, 447 Md. at 104 (emphasis added), but permitting 

authorities have discretion to include water quality based effluent conditions in addition to 

the MEP standard to protect water quality. Carroll County, 465 Md. at 220–21; id. at 214 

(“[A]n 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.”). Since 1990, the EPA has 

“‘recommend[ed] 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.’” Id. at 222 (quoting EPA Letter to Maryland 

Department of the Environment re Supplemental Comments on Frederick County Phase I 

MS4 Permit (Sept. 23, 2014)). 

The Department imposes water quality standards on MS4 operators that incorporate 

the “assumptions and requirements of wasteload allocations,” Carroll County, 465 Md. at 

193 (cleaned up), through use of an impervious acre metric that acts as a surrogate for 

4 “‘Water quality standards’ are targets set by the states and approved by the EPA.” 

Maryland Small MS4 Coal., 479 Md. at 9 (citing 33 U.S.C. § 1313).
7

Chesapeake Bay stormwater WLAs. When a state identifies impaired waters (waters where 

technology-based effluent limitations in NPDES permits are not stringent enough to ensure 

water quality), it must establish a TMDL for every pollutant that prevents the water from 

meeting water quality standards. 33 U.S.C. § 1313(d)(1). The TMDL describes a numeric 

cap or “‘level’ of a pollutant that a water body can tolerate without violating applicable 

water quality standards.” Carroll County, 465 Md. at 190. A TMDL is made up of the sum 

of individual WLAs for point sources and load allocations (“LAs”) for nonpoint sources 

plus natural background. 40 C.F.R. § 130.2(i). 

The EPA issued the Chesapeake Bay TMDL in 2010. See Carroll County, 465 Md.

at 194. It requires Bay jurisdictions, including Maryland, to reduce discharges of pollutants 

for which the Bay has failed to attain target water quality standards—i.e., nitrogen, 

phosphorus, and sediment—by 2025. Id.; Anacostia Riverkeeper, 447 Md. at 106–07, 109. 

And “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.” Carroll County, 465 Md. at 193; Anacostia 

Riverkeeper, 447 Md. at 123 (the impervious surface restoration requirement is a 

“surrogate or proxy” effluent limitation with a water quality-based standard, and only 

indirectly reduces pollution). “TMDLs inform,” Anacostia Riverkeeper, 447 Md. at 100, 

but “WLAs are more akin to restrictions.” Id. at 104. As such, TMDL WLAs require 
8

“translation pursuant to 40 C.F.R. § 122.44(d)(1)(vii)(B)”5 into permit limits. Id. at 133. 

But those water quality standards, in the MS4 context, are “like the MEP standard, flexible 

as to how a permitting authority complies” with its obligation “to establish effluent 

limitations that take into account WLAs[.]” Id. at 134–35. The text of the regulation, 40 

C.F.R. § 122.44(d)(1)(vii)(B), “does not instruct the permitting authority as to how it must 

ensure this consistency,” but “[i]nstead, the EPA set a minimal, flexible requirement in 

which the permitting authority is to design a scheme where effluent limits are compatible 

or in agreement with WLAs.” Id. at 136. And “the overarching federal law for MS4s—33 

U.S.C. § 1342(p)(3)(B)(iii)—is broad and flexible,” even with respect to the water quality 

based effluent limitations. Id. at 137; see also id. at 179 (citing 40 C.F.R. 

§ 122.44(d)(1)(vii)(B)) (the EPA “has afforded permitting agencies such as [the 

Department] the flexibility to develop effluent limitations”).

3. Maryland’s impervious surface restoration (“ISR”) strategy.

In order to meet Bay TMDL water quality targets, the EPA directed Maryland to 

create watershed implementation plans (“WIPs”) that provide a roadmap for how it would 

achieve the Bay TMDL’s goals for reducing pollution. Carroll County, 465 Md. at 194–

5 The regulation requires the Department to establish effluent limitations that take 

TMDL WLAs into account:

When developing water quality-based effluent limits under this 

paragraph the permitting authority shall ensure that[] . . . 

[e]ffluent limits developed to protect a narrative water quality 

criterion, a numeric water quality criterion, or both, are 

consistent with the assumptions and requirements of any 

available wasteload allocation for the discharge prepared by 

the State and approved by EPA . . . . 
9

95. Maryland developed its WIPs in three different phases. Maryland’s first phase (the 

“Phase I WIP”) committed the State to reducing the adverse effect of MS4 discharges by 

an amount equal to retrofitting twenty percent of the State’s impervious area to restore the 

areas’ pollution-trapping capabilities. This retrofitting is called the “ISR strategy.” The ISR 

strategy is a water quality-based effluent limitation that operates “in addition to” the MEPlevel programs. See id. at 211–12. At times, it also supports the MEP standard. Maryland 

Small MS4 Coal., 479 Md. at 42.

“Impervious surfaces that do not absorb rainwater have long been recognized as a 

key cause of water pollution and the resulting impairment of water quality, particularly in 

urban areas.” Id. at 15. Restoration can involve replacing an impervious surface with 

material that allows for absorption of stormwater, in order to “function more like a natural 

terrain that absorbs and filters rain water.” Carroll County, 465 Md. at 195. Environmental 

groups largely favor such “green infrastructure,” which, according to the Environmental 

Advocates, can “include constructed wetlands, rain gardens, protecting large open natural 

spaces, or planting trees along city streets and greening alleyways.” 

Maryland is now on Phase III of the WIP strategy, which requires Baltimore City 

and County to restore ten percent of their impervious areas during the five-year MS4 permit 

term (in addition to maintaining all of the restoration achieved in Phase I). One important 

aspect of the Department’s implementation of the statewide ISR strategy is the “credits to 

acres approach,” which allows jurisdictions to avoid the costly green infrastructure projects 

with practices that more indirectly impact water quality and stormwater volume. To detail 

these practices, the MS4 permits incorporate two documents by reference: the 2000 
10

Maryland Stormwater Design Manual (“Design Manual”) and the Accounting for 

Stormwater Wasteload Allocations and Impervious Acres Treated Guidance for [NPDES] 

Stormwater Permits (2021) (the “Accounting Guidance”). The Design Manual provides 

guidance on how to size, design, select, and locate alternative BMPs to meet Maryland’s 

WIP performance standards, Anacostia Riverkeeper, 447 Md. at 112, while the Accounting 

Guidance provides a “credits to acres approach” that translates pollutant reduction qualities 

of BMP into credits for acres restored. Id. at 109, 159–60. The credits assigned by the 

Accounting Guidance provide flexibility to permittees to determine how best to satisfy the 

Bay TMDL’s pollution allocations based on local conditions and resources. These credits 

allow jurisdictions to utilize “alternative BMPs” such as street sweeping, storm drain 

cleaning, stream restoration, and tree planting to meet the ISR requirement. Permittees’ 

authority to choose alternative BMPs and the effectiveness of the BMPs strikes at the heart 

of the present challenge to the permits. 

C. Earlier Maryland Decisions On MS4 Permits.

MS4 permitting challenges have made their way up to the Maryland Supreme Court 

three times—sometimes for being too strict and sometimes for being too lax, depending on 

who is seeking review. The first case involved “large” MS4 permits, the second involved 

“medium” jurisdictions, and the last challenged “small” MS4 permits.6 In Anacostia 

Riverkeeper, environmental advocates challenged permit terms as not stringent enough to 

satisfy the Clean Water Act. In Carroll County, the counties argued that their respective 

6 Baltimore County and Baltimore City are categorized under the Clean Water Act as 

“large MS4s.” See 40 C.F.R. § 122.26(b)(4).
11

permits were too stringent and exceeded the Department’s authority under the Act. And 

lastly, in the Maryland Small MS4 Coalition case, the permittee county asked the Maryland 

Supreme Court to reconsider its holding in Carroll County. In all three cases, the Maryland 

Supreme Court affirmed the Department’s authority to issue the permits in question. 

1. Anacostia Riverkeeper 

In this 2016 Maryland Supreme Court decision, Anacostia Riverkeeper and other 

environmental groups—including two of the parties here, Blue Water Baltimore and the 

Chesapeake Bay Foundation—challenged large MS4 permits for not being stringent 

enough. 447 Md. at 95 n.1. The primary contention was that the twenty percent ISR

requirement imposed on jurisdictions was “too opaque” and undefined to comply with 

federal and state law. Id. at 123. In other words, the challengers contended that the MS4 

permits allowed for too much flexibility for permittees’ compliance because they could 

choose their own BMPs from the State’s Design Manual. See id. at 125. 

The Court held that MS4s are not required to impose strict numerical limits that 

would otherwise be required in a typical “end-of-pipe” NPDES permit:

MS4s are subject to the MEP standard under 33 U.S.C. § 1342. 

MS4s are not, however, required to impose effluent limitations 

necessary to meet water quality standards. The [Clean Water 

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 WLAs of EPA-approved 

TMDLs. 

Id. at 104 (emphasis added). The Court also held that the Department had established a 

sufficient performance standard in its Design Manual from which “Counties may choose 
12

from to fulfill the 20% restoration requirement.” Id. at 125. “Because 33 U.S.C. 

§ 1342(p)(3)(B)(iii) does not require a specific performance standard, and because the 

concepts of restoration and impervious surface ‘not restored to the MEP’ are sufficiently 

clear as to the controls that the Counties must install, the 20% restoration requirement in 

the Permits complies with the MEP standard.” Id. at 126; see also id. at 133 (“[W]e uphold 

the Guidance as a component the Counties may legally use to achieve the 20% restoration 

requirement.”). The Court held that the ISR requirement satisfied both the State stormwater 

permitting standards (that incorporate water quality standards) and the MEP standard in 

the Clean Water Act. Id. at 126, 128–29.

2. Carroll County 

Three years later, the Supreme Court clarified the relationship of these separate legal 

standards in Carroll County. 465 Md. at 222–23. This MS4 challenge came from the 

opposite side, with the counties suing the Department for making permit conditions too 

strict. There, the parties agreed the ISR requirement was “a water quality based control that 

[wa]s in addition to those provisions included under the MEP standard,” but one county 

contended that requiring permittees to go beyond the MEP standard in the statute was 

unlawful. Id. at 213 (emphasis added). The Court narrowed its holding by stating that the 

question in Anacostia Riverkeeper “was whether the [ISR] requirement satisfied the MEP 

standard whereas in [Carroll County] the question is whether it unlawfully exceeds it.” Id.

at 214. 

The Court upheld the permits. In the course of analyzing them, the Court considered 

that under the Clean Water Act, MS4 permits “‘shall require controls to reduce the 
13

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.’” Id. at 215 (quoting 33 U.S.C. § 1342(p)(3)(B)(iii)) (emphasis added). 

The Court held that the phrase “such other provisions” authorized the Department to 

include permit conditions that “are not limited by the MEP standard,” including conditions 

that require compliance with water quality standards. Id. at 217. 

In order to “[h]armoniz[e] MS4 [p]ermit [t]erms with the TMDL [p]rocess” the 

Court clarified that there is no practicability analysis with respect to water quality 

compliance in MS4 permits: 

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 the level of water quality to be 

achieved by water quality based effluent limitations on point 

sources is derived from, and complies with, all water quality 

standards. The EPA’s rationale is that deriving 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. 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. . . . 

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.

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 
14

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. 

Id. at 222–23 (cleaned up) (emphasis added). 

The Court explained that the ISR “permit term is a numeric water quality based 

effluent limitation” that is authorized by 33 U.S.C. § 1342(p)(3)(B)(iii). Id. at 234. Even 

still, NPDES permits for MS4s are more flexible and implement pollution mitigation 

programs as surrogates compared to the typical NPDES requirements. Id. at 234–37. The 

Court found that the ISR term in the counties’ permits “correspond[ed] 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 . . . .” Id. at 238. The Court added that “[t]o the extent that the 

Counties challenge restoration provisions in their permits that derive from EPA-approved 

local TMDLs, such challenges should have been made when the local TMDL was approved 

by the EPA and are not appropriately part of judicial review of an MS4 permit in State 

court.” Id. at 264.

One county also challenged the twenty percent ISR requirement as arbitrary and 

capricious because “compliance with the permit’s requirements within five years was 

financially and logistically impossible.” Id. at 225. The Court rejected this challenge, 

stating that “[t]he fact that an agency does not change a proposed action . . . in light of 

comments requesting a change does not mean that the process lacked a meaningful 
15

opportunity for comment or that the agency failed to consider those comments.” Id. at 226. 

Further, the Court found that there was “a rational basis for saying that the restoration 

requirement is necessary for consistency with the Bay TMDL and the Maryland WIP” and 

thus it was reasonable for the ISR requirement to be included in the permit. Id. at 226–27. 

3. The Maryland Small MS4 Coalition Case

In this most recent MS4 case decided in 2022 (after the current permits were issued), 

Queen Anne’s County brought an action for judicial review of its small MS4 permit and 

asked the Maryland Supreme Court to reconsider its holdings in the Carroll County case 

and hold that the “such other provisions” language of 33 U.S.C. § 1342(p)(3)(B)(iii) does 

not authorize the Department to impose requirements that exceed the MEP standard. 479 

Md. at 6. The Supreme Court declined the invitation. Instead, it clarified that Anacostia 

River and Carroll County are not inconsistent with the MEP standard:

In response to challenges from environmental groups, the 

Anacostia Riverkeeper decision concluded that the permit 

conditions in question satisfied the baseline MEP standard. In 

response to a converse challenge from permittees, the Carroll 

County decision concluded that the Act authorizes permit 

conditions beyond the MEP standard for the purpose of 

satisfying water quality standards. Together, the two decisions 

stand for the proposition that MS4 permit conditions must meet 

the MEP standard, but may do more to protect the water quality 

of a waterway. These two holdings are not in conflict with one 

another.

Id. at 33.

The Court elaborated on the relationship between the MEP standard and the water 

quality standards necessary for TMDLs, stating that permit conditions must satisfy the 

MEP standard, but may do more. Id. at 42–43. “This supplementary relationship” 
16

analogizes “the relationship between technology-based effluent limitations and water 

quality limitations in typical NPDES permits.” Id. at 43. “In both types of permits,” the 

Court continued, “there is a minimum standard, and in both types of permits the permitting 

authority may increase the stringency of those standards to protect water quality.” Id.

D. Baltimore County’s & Baltimore City’s MS4 Permits.

1. Public notice and comment period.

Against this abridged regulatory backdrop, we turn to the specific permits before us 

in this appeal. The Environmental Advocates7 sue to overturn the MS4 permits the 

Department issued to Baltimore City and Baltimore County. Draft permits were issued in 

October 2020, underwent a public notice and comment period, see EN §§ 9-324, 1-601 et 

seq., and went into effect November 5, 2021. In our view, the final permits were not 

meaningfully different from the drafts. 

7 The Chesapeake Bay Foundation is a conservation organization “whose mission is to 

‘Save the Bay’ and keep it saved” at least in part by “[r]educing urban and suburban 

stormwater pollution . . . .” Blue Water Baltimore is an organization “focused on 

restoring the health of Baltimore’s rivers, streams, and harbor to the benefit of our 

environment and communities.” In doing so, it “conducts long-term water quality 

monitoring in the tidal Patapsco River and its tidal tributaries, non-tidal tributaries in 

the Jones Falls and Gwynns Falls watersheds, as well as Herring Run, a tributary of the 

Back River.” 

The appellants also include individuals whose affidavits were used to establish standing 

under EN § 1-601(c). The City took issue in its brief with the appellants’ attempt to rely 

on these affidavits as evidence, but the substance of those affidavits was part of the 

administrative records, and we limit our review to what was before the Department 

during the public comment period. EN §1-601 et seq.; Md. Rules 7-201 et seq.

As mentioned before, we’ll refer to all appellants as they labeled themselves in their 

briefs: the “Environmental Advocates.” 
17

During the statutory comment period, the Environmental Advocates took the 

position that the draft permits “lack[ed] specificity and focus needed to deliver reduction 

in stormwater runoff.” More specifically, they attacked the draft permits for relying on ISR 

“equivalent standard[s],” which, they said, “fail[] to meaningfully reduce pollutant loads 

to local waters even though it may minimally reduce nutrient and sediment loads to the 

bay.” They added that “[t]he permits also fail to acknowledge changing weather patterns 

linked to climate change” and urged the Department to “[r]evise the [MEP] standard to 

reflect specific, individual pollutant load reduction goals.” 

In support of their arguments, the Environmental Advocates provided the 

Department with its own data showing, in their view, that “[w]ater [q]uality is not 

improving as a result of our current MS4 permitting regime.” Blue Water Baltimore 

explained that it “routinely collect[s] scientifically rigorous water quality data for a full 

suite of parameters at 49 stations throughout the Jones Falls and Gwynns Falls watershed, 

as well as the tidal Patapsco River and the tributaries that feed into it” and highlighted 

“several key findings.” Among them were “significantly improving trends in Enterococcus

bacteria” but also “significantly worsening trends” involving “polluted stormwater runoff”:

For example, 23 of our 27 nontidal stations (85%) showed a 

worsening trend for at least one of the following parameters: 

Total Nitrogen (mg/L), Total Phosphorus (mg/L), Specific 

Conductance (uS/cm), or Turbidity (NTU) across all weather 

types over a 7-year time period. Only 2 stations showed a 

statistically significant improvement for a single measurement 

of water health.

* * *

Interestingly, our 7-year nontidal dataset covers the previous 

MS4 permit term, suggesting to Blue Water Baltimore that the 
18 

current approach to stormwater management in Baltimore 

City, namely street sweeping, is not improving water quality. 

We similarly question whether Baltimore County’s approach 

is keeping pace with climate change, a growing suburban 

population, and increased development. We believe our data 

suggests that substantial changes, including greater reliance on 

stormwater interventions that reduce stormwater volumes, and 

treat stormwater before it enters our waterways, are necessary 

if we expect to see future water quality improvements. 

The letter urged the Department to require green infrastructure and to reduce the amount 

of ISR credit from alternative BMPs like street sweeping, septic pump-outs, and stream 

restoration. 

Blue Water Baltimore also urged the Department to consider Baltimore City and 

Baltimore County together to relieve “inequity”: 

By allowing under-compliance with stormwater remediation 

requirements within the Patapsco or Back River watersheds in 

[Baltimore] County, [the Department] is allowing a more 

affluent, predominantly white, and populous jurisdiction to 

eschew pollution and volume reductions to the detriment of the 

less populous, predominantly Black, and less affluent 

downstream neighbor, Baltimore City. Under-compliance in 

Baltimore County will not necessarily impact County 

residents; but instead, will impact City residents, already 

suffering from unmitigated stormwater, poor water quality in 

receiving waterways, increased flood volumes, and associated 

public health impacts and property damage. 

The permittees also participated in the public comment process. Local governments 

urged the Department to “defer to the Permittees to determine what constitutes MEP” based 

on fiscal and policy considerations. According to the permits, “the Department . . . solicited 

ideas, concerns, and available data related to restoration implementation. These discussions 
19

were an open, ongoing dialogue with the regulated community relating to restoration 

practices and permit requirements over several years.” 

2. Terms and conditions of the permits at issue.

Despite the recommendations of the Environmental Advocates, the Department 

issued the MS4 permits simultaneously on November 5, 2021, and they appear to be 

substantially similar to the draft permits. Part III of the permits, titled “WATER 

QUALITY,” requires the jurisdictions to “manage, implement, and enforce stormwater 

management programs” that comply with federal law and to comply with the following 

requirements: 

1. Effectively prohibit pollutants in stormwater discharges 

or other unauthorized discharges into, through, or from 

the MS4 as necessary to comply with Maryland’s 

receiving water quality standards; 

2. Attain applicable stormwater wasteload allocations 

(WLAs) for each established or approved Total 

Maximum Daily Load (TMDL) for each receiving 

water body, consistent with Title 33 of the U.S. Code 

(USC) § 1342(p)(3)(B)(iii); 40 CFR § 122.44(k)(2) and 

(3); and 

3. Comply with all other provisions and requirements 

contained in this permit, and in plans and scheduled 

developed in fulfillment of this permit. 

The permits provide that compliance with that Part satisfies the MEP standard and 

represents “adequate progress toward compliance with Maryland’s receiving water quality 

standards and U.S. [EPA] established or approved stormwater WLAs for this permit term.”

Part IV of the permits, titled “STANDARD PERMIT CONDITIONS,” provides for 

stormwater management programs and stormwater restoration. With respect to the ISR 
20

requirement for stormwater restoration, the permits state that “MS4 permits must require 

stormwater controls to reduce the discharge of pollutants to the MEP and such other 

provisions as the Department determines appropriate for the control of such pollutants.” 

The permits also provide that they must be consistent with stormwater WLAs of TMDLs 

and that they are. The City and County are required, by the end of their permit terms, to 

restore an additional 3,696 and 2,696 acres, respectively. For example, Baltimore City’s 

MS4 permit requires the following: 

1. Annual alternative control practices used by Baltimore 

City to meet its prior MS4 permit’s impervious acre 

restoration requirement shall be: 

a. Continued annually at the same level of 

implementation (e.g., street lane miles swept, 

catch basin cleaning) under this permit;

b. Replaced with 5,701 impervious acres using 

stormwater management BMPs, programmatic 

initiatives, or alternative control practices in 

accordance with the 2021 Accounting Guidance; 

or

c. A combination of a and b above. 

2. The impervious acre restoration requirements described 

below are in addition to the requirements listed [above]. 

The permits give the jurisdictions flexibility to implement the ISR strategy “by 

implementing stormwater BMPs, programmatic initiatives, or alternative control practices 

in accordance with the 2021 Accounting Guidance . . . as long as the total restoration at the 

end of year one meets the implementation benchmark schedule” in the permits. The 

jurisdictions also must submit annual implementation plans to the Department for approval, 

as well as annual BMP effectiveness monitoring. 
21

E. Judicial Review.

On December 3, 2021 and December 6, 2021, the Environmental Advocates filed 

petitions for judicial review of the MS4 permits in the Circuit Court for Baltimore County

and the Circuit Court for Baltimore City, respectively. The circuit courts affirmed the 

Department’s final determination to issue the permits. The Environmental Advocates filed 

timely notices of appeal, and this Court consolidated the appeals on motion of the 

Environmental Advocates on May 2, 2023.

II. DISCUSSION

This appeal asks three questions about what is required legally of these MS4 permits 

by state and federal law and whether there is competent, substantial evidence in the record 

to support the Department’s determination that those standards are met by these permits. 

The Environmental Advocates attack the permits by asking this Court to resolve three 

questions:8 First, “Do the Permits violate federal or state law by not ensuring compliance 

8 The Department (and, by adoption, the County, see Md. Rule 8-503(f)) phrased the 

Questions Presented as follows: 

1. Do the Permits’ restoration requirements, derived from 

the Chesapeake Bay total maximum daily load and Maryland’s 

Phase III Watershed Implementation Plan, and scientifically 

verified by the Chesapeake Bay Program, protect water 

quality?

2. Do the Permits’ restoration requirements constitute 

unlawful backsliding when they are water quality-based 

effluent limitations that require additional restoration from 

what the Permits’ previous iterations required?

3. Do the Permits consider climate change and impacts on 

City residents, because (a) they require pollution reduction 

Continued . . . 
22

with water quality standards?” Second, “Do the Permits violate federal or State law by 

allowing unlawful backsliding?”9 And third, “Do the Permits violate federal or State law 

by failing to consider the substantial evidence in the record related to climate change, 

disproportionate impacts, and ineffective stormwater management controls?” 

The Environmental Advocates argue that the Department applied the wrong legal 

standards in drafting the terms of the permits and that it acted arbitrarily and capriciously 

by failing to issue permits that would meet mandated water quality standards. The 

Department responds that the Environmental Advocates “seek[] to impose additional 

standards on the Department” not required by state and federal law and the permits are 

otherwise supported by competent, substantial evidence. We agree with the Department 

practices that also manage stormwater volume and (b) afford 

the City with flexibility to address impacts on City residents? 

The City phrased its Questions Presented as follows:

1. Did MDE’s determination to issue the City’s permit violate 

federal or State law regarding water quality standards given the 

Court of Appeals’ (now Maryland Supreme Court) opinion in 

Anacostia Riverkeeper? 

2. Did MDE’s determination to issue the City’s MS4 permit 

violate federal or State law prohibiting backsliding when it 

imposes new and continuing restoration requirements?

3. Did MDE’s determination to issue the City’s MS4 permit 

violate federal or State law when there are no legal 

requirements for an MS4 permit to include requirements 

related to climate change and community impacts?

(Footnote omitted). 

9 “Backsliding” refers to permits which “contain effluent limitations which are less 

stringent than the comparable effluent limitations in the previous permit.” 33 U.S.C. 

§ 1342(o)(1). 
23

that the record supports its decision to issue the permits and we affirm the judgments of the 

circuit court. 

A. Standards of Review.

It’s important to define the narrow issue before us and our limited role as a 

reviewing court. The Environmental Advocates don’t (and can’t) challenge the Bay TMDL 

or Maryland’s Phase III WIP. See Carroll County, 465 Md. at 264 (no judicial review of 

EPA-approved TMDLs). By statute, we review only the agency’s decision to issue each 

permit against the administrative record before the Department, EN § 1-601(d), 1-606(c), 

and we determine whether the permitting decision is legally correct and supported by 

competent, substantial evidence, and determine whether the agency action is arbitrary and 

capricious. Maryland Small MS4 Coal., 479 Md. at 30; Anacostia Riverkeeper, 447 Md. at

120–21. In addition, we “review[] the agency action itself rather than the decision of the 

circuit court.” Carroll County, 465 Md. at 201. 

Factual findings, the review of matters committed to the Department’s discretion, 

and our review of the Department’s legal conclusions are all subject to different standards 

of review. See id. at 201–04. First, when reviewing factual findings by the Department 

under the “substantial evidence” standard, we “defer[] to the facts found and inferences 

drawn by the agency when the record supports those findings and inferences. . . . [W]ith 

respect to factual issues that involve scientific matters within an agency’s area of technical 
24

expertise, the agency is entitled to ‘great deference.’” Id. at 201–02 (citing Anacostia 

Riverkeeper, 447 Md. at 120) (citation omitted). 

Second, when reviewing the Department’s discretionary decisions, we apply the 

“arbitrary and capricious” standard, which also affords great deference to the Department. 

Id. at 202. “[G]enerally the question is whether the agency exercised its discretion 

‘unreasonably or without a rational basis.’” Id. (quoting Harvey v. Marshall, 389 Md. 243, 

297 (2005)). For purposes of MS4 permitting, we may consider federal administrative case 

law and “should affirm decisions of ‘less than ideal clarity’ so long as the court can 

reasonably discern the agency’s reasoning.” Id. (quoting Bowman Transp., Inc. v. Ark.-

Beset Freight Sys., Inc., 419 U.S. 281, 285–86 (1974)). 

Third, when reviewing the Department’s legal conclusions, we “accord[] the agency 

less deference than with respect of fact findings or discretionary decisions.” Id. at 202–03. 

We won’t uphold an action based on legal error, but we “give careful consideration to the 

agency’s interpretation” of laws the Department has been charged to administer. Id. at 203. 

B. There Is Competent, Substantial Evidence That The Permits 

Comply With Applicable State And Federal Water Quality 

Standards. 

The heart of the Environmental Advocates’ challenge to the permits lies in their 

contention that pollution reduction data from the past seven years reveals that the 

Department has issued ineffective MS4 permits in the past. As drafted, they contend, the 

Department has acted arbitrarily and reached conclusions not supported by the evidence in 

the administrative record, and thus the permits violate federal and state law because they 

don’t ensure compliance with water quality standards. The Department disagrees as a 
25

factual matter and responds that “the Permits ensure conformity with water quality 

standards because the restoration requirement is consistent with the goals and assumptions 

of the Bay TMDL.” We agree, given the deference owed to the Department here, that the 

Department had a rational basis for implementing permit terms it found were consistent 

with applicable WLAs. 

1. The Department exercised its discretion to implement water 

quality based effluent limitations in the permits.

As a threshold matter, we address the City’s contention that MS4s are not required 

to comply with water quality standards. The City contends that Anacostia Riverkeeper’s 

holding that “MS4s are not subject to the requirement of imposing effluent limitations

necessary to meet water quality standards,” 447 Md. at 102 (cleaned up), “is controlling 

and dispositive” and “the standards referenced by Appellants are inapplicable to the City’s 

MS4 permit.” This overstates the holding of Anacostia Riverkeeper. The Department 

exercised its discretion and implemented water quality-based effluent limitations in the 

permits akin to those in the Carroll County decision. As the Department concedes, the 

permits’ restoration requirement is, at least in part, a water quality-based effluent 

limitation. This means that the ISR requirement must be consistent with applicable WLAs

per 40 C.F.R. § 122.44(d)(1)(vii)(B). But again, the Department has a lot of flexibility in 

how it achieves this consistency in the permits, and the permits here are valid. 

2. The Department has broad discretion in how it achieves 

consistency with TMDL WLAs.

To the extent that the Environmental Advocates seek to challenge the ISR 

requirement, including use of alternative BMPs and the “credits to acres” approach of the 
26 

Accounting Guidance, this contention is foreclosed by the Maryland Supreme Court’s 

decision in Anacostia Riverkeeper. 447 Md. at 128–29. In that case, the Court approved 

the use of such a flexible, “iterative” approach to meet TMDL WLAs. Id. at 135 (“iterative” 

process incorporating WLAs complies with 40 C.F.R. § 122.44(d)(1)(vii)(B)). The permits 

here take the same approach—under each, the jurisdiction provides specific 

implementation plans that detail how it will implement adequate progress toward TMDL 

WLAs. 

To the extent that the Environmental Advocates dispute the effectiveness of the ISR 

strategy (namely, the credits assigned to alternative BMP like street sweeping), that raises 

factual issues that lie within the Department’s scientific discretion. The Environmental 

Advocates argue that “[i]n the past and the current permit, the Department has allowed 

Baltimore City to rely in large part on alternative practices such as street sweeping that do 

nothing to mitigate the flow and volume of polluted stormwater. Nor have these practices 

resulted in observable or quantifiable improvements to local water quality.” We give 

deference to the Department in its ISR strategy and apply the “arbitrary and capricious” 

standard. Carroll County, 465 Md. at 202. “[G]enerally the question is whether the agency 

exercised its discretion ‘unreasonably or without a rational basis.’” Id. (quoting Harvey, 

389 Md. at 297). And in the administrative record below, Blue Water Baltimore presented 

evidence that “[w]ater [q]uality is not improving as a result of our current MS4 permitting 

regime.” It cited to evidence that pollutant trends are not improving, which it characterized 

as “suggesting . . . that the current approach to stormwater management in Baltimore City, 

namely street sweeping, is not improving water quality.” (First emphasis added.) The 
27

Environmental Advocates cite their backward-looking data to argue that the alternative 

BMPs haven’t worked to reduce stormwater pollutants. 

The Department responded that Blue Water Baltimore’s data is unreliable, first

because it lacks any causation analysis within that data that support the conclusion that 

declining trends are due to alternative BMPs. The Department argues the Environmental 

Advocates “fail to account for other sources of pollution,” which is why they can only 

“suggest[]” the data support their conclusions. The Department insists that the data lacks 

any causal connection demonstrating that the trends are attributable to the City’s or 

County’s enforcement of the permits, especially when the data accounts for such a vast 

area. In its Response to Comments, the Department responded specifically that “alternative 

BMPs are often an effective and necessary tool to address local flooding. . . . Keeping 

storm drain systems free of debris improves the capture and conveyance of runoff and 

effectively reduces local flooding.” 

Second, the Department cites an expert panel report on street sweeping and storm 

drain cleaning that forecasts estimated future reduction in pollution and recommendations 

for counting credits for street and storm drain cleaning. Recommendations of the Expert 

Panel to Define Removal Rates for Street and Storm Drain Cleaning Practices (May 19, 

2016). The expert report noted “a strong empirical basis for modeling how solids are 

transported from the street to the storm drain” and that “[s]treet cleaning may be an 

excellent strategy to reduce the toxic inputs from urban portions of the Chesapeake Bay 

watershed.” See also Anacostia Riverkeeper, 447 Md. at 107–09, 177 n.107 (use of 

monitoring, modeling, and “efficiency estimates” comply with the MEP standard). 
28

The Environmental Advocates view the Department’s rejection of their data as 

arbitrary and capricious. But the Department had a rational basis to reject Blue Water 

Baltimore’s speculation that the alternative BMPs failed to manage stormwater and

improve water quality. Water quality standards in the MS4 context are “like the MEP 

standard, flexible as to how a permitting authority complies” with its obligation “to 

establish effluent limitations that take into account WLAs[.]” Anacostia Riverkeeper, 447 

Md. at 134–35. Here, “the EPA set a minimal, flexible requirement in which the permitting 

authority is to design a scheme where effluent limits are compatible or in agreement with 

WLAs.” Id. at 136. Although we agree that the Environmental Advocates offered data to 

back their claims, the Department wasn’t required absolutely to follow it, and we must be 

“extremely deferential” to an agency with respect to this scientific matter committed to its 

discretion. Carroll County, 465 Md. at 202 (cleaned up). The Department did not act 

arbitrarily and capriciously in rejecting Blue Water Baltimore’s conclusions about the 

effectiveness of the alternative BMPs under these circumstances.

We take the Environmental Advocates’ concerns seriously, and they have raised 

genuine factual disputes about the future efficacy of the permit conditions. But the 

Department resolved those disputes on the merits against the Advocates’ position, and the 

law affords the Department wide flexibility in choosing “best management practices” that 

are “consistent” with WLAs—flexibility to which we, as a reviewing court, defer so long 

as there was substantial evidence to support it, which there was. “The fact that an agency 

does not change a proposed action . . . in light of comments requesting a change does not 

mean that the process lacked a meaningful opportunity for comment or that the agency 
29

failed to consider those comments.” Carroll County, 465 Md. at 226. And because there 

was competent, substantial evidence for the Department to conclude that the permits 

comply with applicable state and federal water quality standards, we uphold the permits. 

C. The Permits Do Not Constitute Unlawful Backsliding.

The Environmental Advocates’ second contention is that the permits violate the 

Clean Water Act’s “anti-backsliding” provision, 33 U.S.C. § 1342(o), because “the current 

permit’s requirement to restore a total of only 10% of additional impervious surface over 

the next permit term” is less than the prior permit’s twenty percent restoration requirement. 

The relevant statute, 33 U.S.C. § 1342(o)(1), provides that in general, future NPDES 

permits may not “contain effluent limitations which are less stringent than the comparable 

effluent limitations in the previous permit.” The statute continues, however, that “in the 

case of effluent limitations established on the basis of section 1311(b)(1)(C) or section 

1313(d) or (e) of this title, a permit may not be renewed, reissued, or modified to contain 

effluent limitations which are less stringent than the comparable effluent limitations in the 

previous permit except in compliance with section 1313(d)(4) of this title.” (Emphasis 

added.) And section 1313(d)(4) allows revisions to effluent limitations for waters with 

corresponding TMDLs so long as “the cumulative effect” will attain water quality 

standards:

where the applicable water quality standard has not yet been 

attained, any effluent limitations based on a [TMDL] or other 

[WLA] established under this section may be revised only if 

. . . the cumulative effect of all such revised effluent limitations 

based on such [TMDL] or [WLA] will assure the attainment of 

such water quality standard . . . .
30

The Department offers two responses: first, although the last permits required 

twenty percent restoration, the new permits require each jurisdiction to continue “annually 

at the same level of implementation” any alternative practices they used to meet its 

previous restoration requirements. Thus, the Department argues, “the Permits’ effluent 

limitations are additional and cumulative effluent limitations on top of previous effluent 

limitations, an approach that generates additional pollution reductions.” Second, the 

Department points out that the exception in 33 U.S.C. § 1313(d)(4)(A) applies because 

even if the restoration requirements were “less stringent” than the previous permits, they 

nevertheless are designed to attain water quality standards. 

We agree with the Department. The permits are cumulative and their new 

requirements add to the requirements from earlier permits, so they aren’t “less stringent 

than the comparable effluent limitations in the previous permit.” In addition, as we held 

with respect to the Environmental Advocates’ first question, the Department had a rational 

basis to conclude that the “cumulative effect” of the ISR strategy would attain the water 

quality standard for the applicable WLAs, in compliance with 33 U.S.C. § 1313(d)(4)(A). 

The Environmental Advocates may disagree, but the Department’s conclusion is rational 

and there’s substantial evidence in the record to support it.

D. The Permits Were Not Arbitrary And Capricious For The 

Department’s Failure To Consider “The Totality Of 

Information.”

The Environmental Advocates’ final contention is that “the Department has issued 

inappropriately segmented permits” that fail to comply with state and federal law. This 

issue really re-casts the first issue, that the permits are ineffective, and our discussion about 
31

the Department’s broad discretion over MS4 permitting addresses it generally. But the 

Environmental Advocates raise several additional problems with the permits that, they 

conclude, cause the permits to fall short on water quality and the MEP standards. Given 

the flexible legal standards and our deferential standard of review, we see no basis to reject 

these permits. 

The Environmental Advocates argue that “[t]he Department’s decision to consider 

the Baltimore County and Baltimore City MS4 Jurisdiction separately harms the 

environment and produces inequitable results.” The Department and City both respond that 

the Environmental Advocates failed to preserve this argument because it was never raised 

in the administrative proceedings. Md. Rule 8-131(a) (“[o]rdinarily, an appellate court will 

not decide any other issue unless it plainly appears by the record to have been raised in or 

decided by the trial court”). Although the Environmental Advocates attacked the permits 

for taking a “separate and fragmentary” approach to the permits, we don’t read their brief 

as raising the specific error that there needed to be a single permit for both Baltimore City 

and Baltimore County. Rather, the Environmental Advocates assert generally that the 

Department failed to consider the permits holistically. 

First, the Clean Water Act authorizes the Department to impose controls on a 

“jurisdiction-wide basis.” 40 C.F.R. § 122.26; 33 U.S.C. § 1342(p)(3)(B)(i). And the 

Environmental Advocates’ position disregards the context of the NPDES program, 

TMDLs, and MS4 permitting. The permits incorporate by reference statewide (the 

Maryland WIPs) and regional (e.g., the Bay TMDL) strategies in enforcing the Clean 

Water Act, which is itself implementing a national policy. The county-level permits feed 
32

this broader objective, and to the extent that the Environmental Advocates view them as 

falling short regionally, those complaints raise essentially the same attack on the efficacy 

of the permit conditions that we addressed above.

Second, the Environmental Advocates argue that “[t]he Department’s failure to 

consider increased rainfall data and Baltimore County’s contribution to the City’s 

Stormwater Burden disproportionately impacts Baltimore City residents.” The crux of this 

argument is that “the final permits lack any meaningful controls or changes to address these 

fundamental stormwater management issues,” and therefore that the permits as a whole 

lack a rational basis. The Department responds that it did “consider[] flooding concerns 

because the practices approved by the [Bay] Program already account for stormwater 

volume and provide the City and County with the flexibility to address local 

conditions . . . .”10

The Department responds that it considered increased rainfall and its impact on the 

discharge of pollutants in “several ways,” chiefly through the Design Manual, which 

devises restoration practices that manage both pollutants and water volume. See Anacostia 

Riverkeeper, 447 Md. at 112, 123–25 (discussing the Design Manual, which implements 

10 In support of this contention, the Environmental Advocates cite repeatedly to 

affidavits admitted by the circuit court for the limited purpose of establishing 

standing in the circuit courts below. The affidavits themselves were not part of the 

administrative record before the Department in its decision-making subject here for 

review, so we don’t consider them as such. See EN §§ 1-601(d), 1-606(c). But at 

oral argument the Environmental Advocates stated that the fact of urban flooding 

was before the Department, as were comments offered by some of the same affiants, 

and the record supports this assertion. So the assertions contained in the affidavits 

are part of the record we review, if not the affidavits themselves. 
33

the ISR requirement “to abate[] the increase in stormwater runoff and the discharge of 

pollutants because of the increase in impervious surfaces”). In light of the flexibility 

afforded jurisdictions in managing MS4 discharges within the statutory scheme, the 

Department’s rationale in affording the City flexibility in managing stormwater is 

reasonable. “[U]rban restoration is difficult due to available space and construction costs. 

Thus, instead of mandating certain kinds of restoration, the Department chose to 

incentivize certain stormwater infrastructure projects, such as those that control stormwater 

volume and mitigate flooding”—to include street sweeping and storm drain cleaning which 

help to manage both pollution and volume. (Citation omitted.) Moreover, the permit

requires the City to solicit public input to address urban flooding. In its Response to 

Comments, the Department contends that it worked to “incentivize[] and support[] actions 

by local governments and community leaders that collaborate to prioritize restoration in 

marginalized communities.”

Finally, the Environmental Advocates argue that the permits are ineffective because 

the Department failed to include “climate change related conditions.” The Department

responds first that the “adequate supporting data simply did not exist” in the administrative 

record the time the permits were issued. Efforts to address effects of climate change in the 

State are ongoing, see EN § 4-203,11 and the Department insists “the State will update the 

11 This statute imposes a duty on the Department to “review and update” stormwater 

management regulations “at least once every 5 years . . . using the most recent 

precipitation data available[.]” EN § 4-203(b)(3). Accordingly, “[a]fter November 1, 

2021, the Department shall report to the General Assembly . . . on any revisions the 

Continued . . . 
34

Design Manual and practices to account for increased precipitation” when more data is 

reported. For that reason, the permits contain “reopener clause[s]” that will allow 

modification based on new information (specifically, Part IV.D.1). The flexible, iterative 

approach complies with the MS4 legal framework. See Anacostia Riverkeeper, 447 Md. at 

135.

We affirm the Department’s decision to issue the 2021 MS4 permits to Baltimore 

City and Baltimore County. The Department complied with 33 U.S.C. § 1342 in 

implementing MS4 permits with controls designed to reduce the discharge of pollutants to 

the maximum extent practicable, and the Department did so in a way that is consistent with 

the assumptions and requirements of applicable WLAs. The cumulative nature of the ISR 

requirement satisfies 33 U.S.C. § 1342(o)(1) and the permits are valid.

JUDGMENTS OF THE CIRCUIT COURTS 

FOR BALTIMORE COUNTY AND 

BALTIMORE CITY AFFIRMED. 

APPELLANTS TO PAY COSTS.

Department intends to make” to stormwater management regulations. EN 

§ 4-203(b)(4). Of course, the permits at issue were effective November 5, 2021, and the 

Department insists the Environmental Advocates “put[] the cart before the horse” in 

seeking to require that the permits account for increased precipitation relating to climate 

change.