Issue Overview – County MS4 Stormwater Permit Litigation

As previously reported on Conduit Street, various environmental groups have initiated lawsuits challenging the National Pollutant Discharge Elimination System (NPDES) Phase I Municipal Separate Storm Sewer System (MS4) permits that the Maryland Department of the Environment (MDE) has been issuing to certain counties.  This issue summary provides an overview of the topic and explains MACo’s position.

What is a NPDES MS4 Permit?

The NPDES MS4 permit system was created by the United States Environmental Protection Agency (EPA) in 1990.  The permits are required for certain local governments (counties and municipalities) and the Maryland State Highway Administration (SHA) and dictate the water quality standards the permitted entity must comply in treating and preventing stormwater runoff.  The stormwater runoff requirements are based on water quality standards set under the federal Clean Water Act (CWA) and the permits have a 5-year term.  In Maryland, MDE sets individual permit requirements and issues the permits, subject to EPA sign-off.

MS4 permits are divided into Phase I and Phase II categories.  Phase I permits apply to “large” local governments (those with a with a population greater than 250,000), “medium” local governments (those with a population between 100,000 and 250,000), and SHA.  The permit requires them to treat or prevent pollution in stormwater runoff to the maximum extent practicable (MEP) in order meet federal water quality standards under the Clean Water Act (CWA).  In Maryland, the following entities are subject to a Phase I permit:  SHA, Baltimore City, and Anne Arundel, Baltimore, Carroll, Charles, Frederick, Harford, Howard, Montgomery, and Prince George’s Counties.

The EPA created Phase II stormwater requirements in 1999.  The permits apply to certain local governments that have a population of at least 1,000.  A Phase II permit holder must implement six measures:  (1) public education and outreach; (2) public participation and involvement; (3) illicit discharge detection and elimination; (4) construction site runoff control; (5) post-construction runoff control; and (6) pollution prevention/good housekeeping.  In Maryland, Cecil and Washington Counties and approximately 60 municipalities are subject to Phase II permits.

MDE NPDES Permit Webpage

Why is there litigation?

The current round of NDPES MS4 permits are the first that must also account for additional requirements under the Chesapeake Bay Total Maximum Load (TMDL).  The first permit to come up for renewal under the Bay TMDL requirements was Montgomery County’s.  After considering how to best incorporate the TMDL requirements, MDE issued a permit renewal to the County in 2010, with EPA’s sign off.  The permit required the County undertake stormwater retrofits on 20% of existing impervious surfaces.

A consortium of environmental groups, including the Anacostia Riverkeeper, Potomac River Keeper, Friends of the Earth, Waterkeeper Alliance, and others challenged the permit, first administratively and then in Maryland circuit court.  The groups alleged the new permit did not meet the CWA and TMDL water quality requirements and lacked needed specificity.

Other environmental groups have since brought similar legal challenges against the MS4 permits for Baltimore City and Anne Arundel, Baltimore, and Prince George’s Counties.

The Circuit Court Decision

Initially the circuit court dismissed the petitioners’ complaint, but the Court of Special Appeals reinstated the claim and remanded the case back to circuit court.  In Anacostia Riverkeeper v. Maryland Department of the Environment (Case No. 339-466-V), the circuit court then found for the petitioners and against MDE and Montgomery County.

The circuit court cited a lack of specific benchmarks, deadlines, and monitoring  provisions in the permit, noting that reliance on best management practices from manuals or other outside policies was insufficient.   The court also concluded that the permit “must include requirements needed to meet water quality standards” under the CWA, state law, and federal regulations.  The conclusion seemed to imply that a strict compliance standard should apply, rather than the traditional MEP.

Circuit Court Opinion and Order

Why Should Counties Care?

If interpreted broadly, the circuit court’s decision could move MS4 permit standards away from the MEP standard, which includes an analysis of cost and feasibility, to a strict compliance standard, which disregards cost and would hold counties liable for meeting their water quality standards no matter how costly or infeasible.

The Court of Special Appeals’ decision in this case will likely apply to all Phase I and Phase II MS4 permit holders and could influence the ongoing MS4 litigation in other counties.

Where is the Case Now?

Subsequent to the circuit court decision MDE and Montgomery County appealed to the Court of Special Appeals.  MDE and Montgomery County have submitted their opening briefs and the Anacostia Riverkeeper has filed its response.

MDE Opening Brief

Montgomery County Opening Brief

Riverkeeper Response to MDE Appeal

What is MACo’s Position?

Counties should comply with the federally-mandated CWA and TMDL requirements, including those incorporated into the MS4 permit process and MACo believes that counties are investing significant resources and effort towards that goal.  However, MACo is concerned that the circuit court ruling could create impossible compliance timelines and eliminate the cost analysis that has traditionally been part of the MEP standard.

Accordingly, MACo joined an amicus curiae (friend of the court) brief that was coordinated by the Maryland Municipal Stormwater Association (MAMSA) in support of the State’s position.  Besides MAMSA and MACo, other brief participants included the National Association of Clean Water Agencies, Wet Weather Partnership, and Baltimore County.

The brief highlighted the consequences of moving from the traditional MEP standard to a strict compliance standard:

To County Amici’s knowledge, the Circuit Court’s Opinion and Order accepting Petitioners’ argument is the first time that any federal or state court in the United States has ruled that the CWA requires MS4 permits to mandate strict compliance with water quality standards. Instead, the statute provides a different legal standard for MS4s – that pollutant discharges be reduced to the “maximum extent practicable,” or “MEP” for short….Unless reversed, the Circuit Court’s Opinion and Order will have harsh financial impacts on Maryland’s families and businesses. It will effectively require MDE to force local governing bodies to raise stormwater utility rates and taxes – to whatever amount is needed – to attempt in a mere five years the monumental task of reversing the effects of centuries of real estate development on water quality in urban and suburban areas so as “to meet water quality standards.”

The Anacostia Riverkeeper and other appellees took the somewhat unusual step of petitioning the Court of Special Appeals to reject the amicus brief, alleging that the brief is misleading, will not aid the court’s decision, and presses a legal position that contradicts the stated position of MDE and Montgomery County.  In the opposition, the appellees did clarify that they are not seeking to have counties comply with all water quality standards within the 5-year life span of the MS4 permit:

Nothing in the Montgomery County Circuit Court’s decision mandates or even suggests that the County must comply with all applicable water quality standards within five years…Nor have Appellees made such a claim in this litigation.

MAMSA and the other amici  challenged the opposition, arguing that amicus brief satisfied the Court’s desirability requirement, did not intentionally misrepresent the Riverkeepers’ position, did not introduce new arguments, and properly cited cost and practicability sources.

The Court of Special Appeals has provisionally accepted the MAMSA amicus brief and also accepted an amicus brief filed by the Chesapeake Bay Foundation.

MAMSA & Local Government Amicus Brief

Riverkeeper Opposition to Amicus Brief

MAMSA Response to Riverkeeper Opposition


This case could have significant consequences for counties subject to MS4 permits.  MACo will continue to monitor and report on the case as it moves forward.

For further information, please contact MACo Legal and Policy Analyst Les Knapp ( or 410.269.0043).