The Chesapeake Bay Agreement seeks to improve water quality within the Chesapeake Bay watershed to a level that will remove the Bay from the federal Clean Water Act 303 (d) list of impaired waters by 2010.  “Pennsylvania’s Chesapeake Bay Tributary Strategy” was released during December 2004 to establish the programs needed to meet the nutrient cap goals of Pennsylvania’s Chesapeake Bay tributaries. 

The Strategy has wide-ranging implications for wastewater treatment plants (WWTPs) in the Chesapeake Bay drainage area because those facilities with average annual design flows of over 2,000 gpd will be issued annual Total Nitrogen (TN) and Total Phosphorus (TP) effluent loading limits based on a concentration of 8 mg/l and 1 mg/l, respectively. 

Those concentrations will be used to develop annual mass loading limits for TN and TP based on 2010 projected flows.  The limits are referred to as cap loads because they will never be increased, except for rare cases. As flows increase above the 2010 projected flows, the TN and TP concentrations must be lowered so that the cap load limits are not exceeded. 

WWTP Considerations

In order to comply with this new requirement, owners of WWTPs will have to undertake facility upgrades.

The most desirable approach for a WWTP to comply with pending TN and TP cap load limits will be proactive, appropriate, site-specific planning before the limits are assigned to a WWTP.