Prince George's County Watershed Assessments and Studies

This webpage reviews information about the Prince George’s County (the County) Department of the Environment’s (DoE’s) stormwater management, watershed assessment, and restoration planning and implementation efforts. Click on the following links for more details on specific topics of interest:



On January 2, 2014, the Maryland Department of the Environment (MDE) issued a new municipal separate storm sewer system (MS4) permit to the County under the National Pollutant Discharge Elimination System (NPDES). An MS4 is a series of stormwater sewers owned by a municipal entity (e.g., the County) that discharges the conveyed stormwater runoff into a water body (e.g., Anacostia River). The County’s 2014 MS4 permit requires that the County develop local restoration plans to address each U.S. Environmental Protection Agency (EPA)-approved total maximum daily load (TMDL).

  1. What is a TMDL?
    • Sometimes referred to as a pollution diet, a TMDL is the calculated maximum amount of a pollutant that a water body can receive without exceeding the water quality standard for that pollutant. A TMDL is represented as a mass per unit of time (e.g., pounds per day), which is known as the load. A TMDL might say, for example, that a maximum load of 1,000 pounds of sediment per day could enter a stream before the stream experiences negative effects. The TMDL for a given pollutant and water body includes the sum of that pollutant from individual point sources (i.e., waste load allocations, or WLAs) and from nonpoint sources (i.e., load allocations, or LAs). The WLA is the portion of the overall pollution diet assigned to permitted dischargers, such as the County’s MS4. The County’s MS4 permit requires that the County develop local watershed restoration plans to address each EPA-approved TMDL with stormwater WLAs.
    •  In 2010, EPA established the Chesapeake Bay TMDL. Each state in the Chesapeake Bay watershed was required to develop Watershed Implementation Plans that serve as a guide for meeting the pollution-reduction targets in the Chesapeake Bay. MDE included the requirement to develop restoration plans in the County's NPDES MS4 permit so that Maryland can inform EPA about actions taken to reduce pollution in the state.
  2. What is a watershed?
    • A watershed is an area of land in which all precipitation eventually drains to a single point via creeks, streams, and rivers. The figure to the right shows the major watersheds in the County.
  3. What is a restoration plan?
    • A restoration plan is a strategy for managing the natural resources within a geographically defined watershed. Restoration plans guide the County’s efforts to prioritize and implement projects to reduce polluted runoff. The plans developed for each of the County’s local watersheds includes requirements to meet the EPA-approved local TMDLs and the Chesapeake Bay TMDL requirements.


Public Engagement

DoE has held several public meetings to inform and engage the community in the County’s development of the local TMDL restoration plans. These meetings allowed the public to ask questions about proposed restoration activities. Details about past public meetings are below.

2021 Tinkers Creek Watershed Restoration Public Meeting: June 29, 2021

 2019 Patuxent River TMDL Restoration Plans Public Meeting: August 27, 2019

 2019 Western Branch Restoration Plan Public Meeting: January 28, 2019

 2014 Local TMDL Restoration Plan Public Meetings

July 23–24, 2014, Public Meetings

 November 12, 2014, Public Meeting:

Watershed Restoration Plans

The County’s watershed restoration plans are strategies for addressing and managing urban stormwater (i.e., runoff originating from rainstorms and snowmelt) to restore and protect the County's water bodies. Stormwater management is most effective when viewed in the watershed context—focusing on watershed land areas and their network of streams that convey stormwater runoff to a common body of water.

In 2014, the County developed and is currently implementing restoration plans that serve as blueprints for improving water quality and meeting pollutant reduction goals called for in approved local TMDLs. Each plan describes: (1) the pollutants and sources of those pollutants specific to each water body, (2) the land uses and natural features in the watershed, (3) a method for determining the amount of pollutant reductions that need to be achieved, and (4) targeted pollutant reduction strategies for each watershed. The strategies include both programmatic initiatives (e.g., pet waste campaign, street sweeping) as well as on-the-ground, pollution-reducing best management practices (e.g., vegetated roadway swales).

Through its County Capital Improvement Program (CIP) and the Clean Water Partnership (CWP), the County has been implementing restoration projects to reduce amounts of nutrients, sediment, bacteria, and other pollutants in stormwater runoff. The Clean Water Map provides information about restoration projects throughout County's watersheds.

The County is continuing to perform restoration planning. The following local TMDL restoration plans met the County’s permit requirements under their 2014 NPDES permit (click to review):

Watershed Restoration Plans Upcoming Updates

From time to time, the local TMDL watershed restoration plans (developed as part of the County’s MS4 requirement) must be evaluated and updated. Recently, MDE updated their guidance on developing nutrient and sediment restoration plans, including how to calculate TMDL progress.  The updated plans will include new timing projections that identify when water quality standards could theoretically be reached based on the forecasting of that watershed’s future restoration projects. The County is currently evaluating and updating the its nutrient and sediment local TMDL restoration plans to include MDE’s latest restoration plan guidance.

In addition, MDE released new guidance on bacteria and PCB restoration plan in early 2022. The County is reviewing the new guidance and develop new countywide bacteria and PCB strategies to cover all applicable watersheds.


Watershed Assessments

The County's 2014 MS4 permit requires that the County conduct watershed assessments by the end of that 5-year permit term. The County completed its comprehensive watershed assessment report in 2018. The MS4 permit indicated that the watershed assessment should include the following items:

  1. Determine current water quality conditions;
  2. Include the results of a visual watershed inspection;
  3. Identify and rank water quality problems;
  4. Prioritize all structural and nonstructural water quality improvement projects; and
  5. Specify pollutant load reduction benchmarks and deadlines that demonstrate progress toward meeting all applicable stormwater WLAs.

 In addition, the County developed Watershed Existing Conditions reports for the watersheds that had EPA-approved TMDLs in 2014. The reports began the watershed assessment process with a compilation and inventory of available information. Links to the 2018 countywide watershed assessment and the 2014 documents are below.

Factsheets for TMDLs within Prince George’s County

The following factsheets summarize each EPA-approved TMDL in the County. Click on the name of the watershed or pollutant name below to review the TMDL factsheet. Complete TMDL reports may be obtained from the MDE TMDL website.

Anacostia River

Chesapeake Bay Watershed

Lower Patuxent River

Mattawoman Creek

Middle Patuxent River

Patuxent River

Piscataway Creek

Rocky Gorge Reservoir

Tidal Anacostia River and Potomac River

Upper Patuxent River

Western Branch

New Upcoming Topics

To be added.

Additional Information

For more information about Prince George’s County's watershed management activities, see or contact Mr. Jerry Maldonado at 240-988-8295 or