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Chesapeake Bay - Wastewater

On December 29, 2010, the U.S. Environmental Protection Agency (EPA) published a final Total Maximum Daily Load (TMDL) for Nitrogen, Phosphorus and Sediment in the Chesapeake Bay. According to EPA's estimates, in 2009, Pennsylvania contributed approximately 108 million pounds (lbs) of nitrogen, 4 million lbs of phosphorus, and 2.6 billion lbs of sediment to the Chesapeake Bay.

Pennsylvania has made significant reductions in the past 30 years, but more work is needed to meet the goals identified in the TMDL. The TMDL requires Pennsylvania to reduce its overall pollutant loading of nitrogen, phosphorus and sediment by 32%, 26%, and 25%, respectively, by 2025.

DEP's strategy for point sources such as wastewater facilities has been to differentiate between significant and non-significant sources of nitrogen and phosphorus.

Sewage facilities with design flows greater than or equal to 0.4 million gallons per day (MGD) are considered significant sources. Industrial waste facilities such as food processors or other manufacturers that discharge more than 75 lbs/day of nitrogen or 25 lbs/day of phosphorus are considered significant sources.

There are over 200 significant sewage and industrial waste dischargers at this time. Significant dischargers receive NPDES permits with annual nitrogen and phosphorus load limits, in lbs/year ("cap loads"). New non-significant dischargers may also receive cap loads.

DEP must manage all point sources so that the actual discharged pollutant load does not exceed Pennsylvania's allocation in the Chesapeake Bay TMDL.

DEP's most recent high-level strategy to address the requirements in the TMDL, the Phase 3 Watershed Implementation Plan (WIP), was finalized in 2019. Section 2 of the WIP focuses on wastewater facilities. DEP decided to develop a more detailed supplement to Section 2 of the WIP that would enable flexibility in managing pollutant loads from wastewater facilities.

This document is updated periodically, i.e., it is dynamic rather than static, and contains DEP's latest permitting strategy with respect to wastewater facilities in the Chesapeake Bay watershed. Click the link below for the latest version of this wastewater supplement document.

DEP has developed an Annual Chesapeake Bay Spreadsheet V2.2 (Excel) for dischargers with cap loads to use to calculate annual loads and report nutrient trading activities. This spreadsheet should be used starting October 1, 2018, and replaces all Chesapeake Bay supplemental reports.

Wastewater Treatment Plants that are buying and/or selling credits must use the current Annual Chesapeake Bay Spreadsheet V2.2 (Excel) (Annual Nutrient Monitoring) to ensure accurate accounting.

The spreadsheet includes macros that must be enabled prior to use and is designed for Microsoft Excel 2007 or later. The spreadsheet includes instructions, but supplemental instructions (PDF) are also available.

For more information you may contact DEP’s Division of NPDES Permitting at