Stormwater Regulation & the County's Efforts

For most urban areas like Montgomery County, what goes into our storm drains ( stormwater) makes its way into our local streams. Those streams are part of larger watersheds that lead to major rivers, like the Potomac River, and eventually the Chesapeake Bay. Because our waters are interconnected and not defined by county or state lines, the federal government regulates everything that goes through storm drain systems.

The federal government hs dedicated its authority to regulate storm drains to the state of Maryland which implements this regulation through a permit process called the Municipal Separate Storm Sewer System Permit Program (AKA the MS4 Permit Program).

Montgomery County has an MS4 Permit that requires the County to meet certain water quality standards. The Permit was reissued on November 5, 2021 and has a term of five (5) years.

NPDES MS4 Permit and Reports

What is the MS4 Permit?

In Maryland, the U.S. Environmental Protection Agency (EPA) has delegated the authority for issuing all NPDES permits in the state, including the MS4 Permits, to the Maryland Department of the Environment (MDE). Read more about the Maryland MS4 Permitting program.

The MS4 Permit Program was established to reduce stormwater pollution throughout the United States. The primary goal of the program is to restore and maintain the chemical, physical, and biological integrity of the nation's waters.

The County's Permit requires the prohibition of pollutants in stormwater and unauthorized discharges to the MS4 restoration of poor quality streams by achieving required pollutant reduction and other activities to help meet water quality protection goals. Runoff must be captured, slowed and treated by stormwater best management practices.

The Department of Environmental Protection is the lead department coordinating a multi-department/agency response to meet the requirements of the MS4 Permit. The permit is a key driver of the County's strategic watershed restoration program.

View the County's MS4 Permit.

MS4 Permit Requirements

The MS4 Permits are issued for a five-year cycle. The County’s previous MS4 Permit was issued on February 16, 2010 and expired on February 15, 2015. It was administratively continued until the new permit is issued on November 5, 2021. When a permit is administratively continued, all the terms and conditions of the existing permit remain fully effective and enforceable. If the County does not comply with the MS4 Permit requirements, it may be subject to civil or criminal fines.

View a map of the completed restoration work for our 2010 MS4 permit.

During the five-year cycle, the County is required to:

Add stormwater management and restore degraded streams
Reduce stormwater pollution to meet water quality goals established through Total Maximum Daily Loads (TMDLs)
Reduce trash and litter county-wide.
Develop and implement a public outreach and education program that focuses on reducing stormwater pollution and litter
Conduct preventive maintenance inspections of all Stormwater management facilities
Implement laws and programs to reduce stormwater and pollution

The 2015 revisions to Section 4-202.1 of the Maryland Environment Article, Watershed Protection and Restoration Programs, require all Maryland Phase I National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit jurisdictions to submit a Financial Assurance Plan (FAP) demonstrating that each jurisdiction will have adequate funding to meet their permit requirement for impervious surfaces restoration. The jurisdictions must submit a FAP to the Maryland Department of the Environment (MDE) by July 1, 2016, and every two years thereafter on the anniversary date of its MS4 permit.

Montgomery County submitted its third Financial Assurance Plan on February 15, 2021.

Montgomery County submitted its first Financial Assurance Plan in July 2016.

The FAP uses the excel spreadsheet required by MDE. It has 6 worksheets, and an executive summary. The first worksheet contains basic MS4 Information and the remaining worksheets contain the following FAP tables:

Table 1: Actions that will be required of the county to meet the requirements of its NPDES Phase I MS4 Permit.
Table 2: Projected annual and 5-year costs for the county to meet the impervious surface restoration plan requirements of its NPDES Phase I MS4 Permit.
Table 3: Projected annual and 5-year revenues or other funds that will be used to meet the cost for the county to meet the impervious surface restoration plan requirements under the NPDES Phase I MS4 Permit.
Table 4: Any sources of funds that will be utilized by the county to meet the requirements of its NPDES Phase I MS4 Permit.
Table 5: Specific actions and expenditures that the county implemented in the previous fiscal years to meet its impervious surface restoration plan requirements under its NPDES Phase I MS4 Permit.

FY18 Financial Assurance Plan

FY16 Financial Assurance Plan

View Council Resolution on the County’s FY16 Financial Assurance Plan (PDF, 107KB)
View the County’s FY16 Financial Assurance Plan (PDF, 1.24MB)
Learn about the Stormwater Fee Bill

Stormwater Regulation & the County's Efforts

What is the MS4 Permit?

MS4 Permit Requirements

2021 Permit Annual Reports

2010 Permit Annual Reports

2001 Permit Annual Reports

Financial Assurance Plan

FY18 Financial Assurance Plan

FY16 Financial Assurance Plan