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Pollutant Reduction Plans are a New Requirement for Many MS4 Communities

Pollutant Reduction Plans (PRPs) are a new requirement for 2018 National Pollutant Discharge Elimination System (NPDES) general permits/Notice of Intents (NOI). PRPs show how the municipality will reduce the pollutant loads going into a waterway. Any municipal separate storm sewer system (MS4) community that either discharges nutrients and sediment to waters in the Chesapeake Bay watershed or to a waterways subject to an impairment must submit a PRP with their permit application, or receive a waiver from the PA Department of Environmental Protection (DEP). To find out if your municipality falls into one of those two categories, go to:

For those discharging into the Chesapeake Bay, they will create a Chesapeake Bay PRP (CBPRP). This will include a schedule to implement best management practices (BMPs) to reduce nitrogen, phosphorus, and sediment associated with existing stormwater discharges into the Bay watershed. For those discharging into an impaired waterbody (whether or not it has a Total Maximum Daily Load (TMDL)), they will create an Impaired Waters Plan. They may also have to create an MS4 TMDL Plan, where applicable.

If a municipality is located within the Chesapeake Bay watershed AND has one or more impaired waterways, they may submit a combined PRP, if they so choose. In addition, municipalities that are located adjacent to one another may submit a joint PRP to DEP, showing how they will work together to address their pollutant load reductions and BMP implementation. A written agreement must document this partnership and highlight the scope of the agreement, roles and responsibilities, cost allocations, and a timeline for implementation.

Contents of a PRP

There are many requirements for PRPs, outlined by DEP here. These include calculating the existing pollutant loads for nitrogen, phosphorus, and sediment, and identifying BMPs to install to reduce those pollutant loads. When selecting BMPs note that their effectiveness must be listed on DEP’s BMP Effectiveness Values document or on the Chesapeake Bay Program’s expert panel report to be considered valid by the DEP.

Public participation is another required element of the PRP. This includes advertising the plan in a newspaper, opening the draft plan up for public comment, scheduling a public hearing to discuss the plan, and recording all comments within the submitted plan. Maps identifying all land uses, impervious surfaces, and storm sewershed boundaries are also required. Finally, the PRP will include funding mechanisms to pay for BMP installation and identification of responsible parties for long-term operation and maintenance of the BMPs. These steps will better ensure successful pollutant reductions.

Resources and Examples

Are you having trouble putting together your PRP? The following resources will provide guidance and examples that may help. DEP’s Municipal Stormwater page also is a good resource.

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