2021 Progress by Source Sector

Most of Maryland's nitrogen and phosphorus loads to the Chesapeake Bay come from human activity with half of that load coming from agricultural activities and the other half coming from development, which includes stormwater and wastewater. In this presentation, wastewater includes loads from septic systems and centralized wastewater treatment plants.

The State looks at each individual source sector, as defined by the Chesapeake Bay Model, to understand how each sector is performing with respect to the State's 2025 targets. Though we tend to focus on the reduction of nitrogen and phosphorus as a metric for success in our annual progress, it is important to consider that the Best Management Practices implemented by the State and its partners are not solely designed to reduce nutrient and sediment pollution. In many cases, they are designed to provide multiple environmental and societal benefits.

In areas where some sectors are lacking, others excel. For instance, while stormwater practices have low nutrient reductions, some are excellent at flood prevention and providing habitat; both qualities that a wastewater plant cannot provide. The table below presents a brief summary of ways in which our restoration practices can achieve multiple benefits.

By choosing practices that treat the most possible needs, it is possible to complement one sector's shortfall with another's strength while maximizing benefits to our citizens and the environment. Maryland's Phase III WIP recommends a variety of practices and allows local jurisdictions flexibility in choosing individual strategies to best meet their needs and build a robust watershed restoration strategy.

Another way of evaluating success is by using our money wisely and choosing practices that provide maximum value for the money spent. In general, agriculture and wastewater are the most cost-effective sectors for reducing nutrient pollution. Urban stormwater practices, while more expensive on a per-pound basis for nutrient reduction, may use different cost effectiveness values that include the co-benefits they provide a community.

Since 1985, Maryland's farmers have reduced their nitrogen and phosphorus loads reaching Chesapeake Bay by 12.18 million pounds per year (N) and 1.2 million pounds per year (P) .

Loads from stormwater are anticipated to remain more or less level, with reductions from implementation being offset by loads from new growth. It will be important, however, for stormwater to increase implementation post-2025 in order to offset the impacts of expected future growth to allow us to remain under our TMDL.

Through 2021, the equivalent of over 30,000 impervious acres have been restored under the Phase I and Phase II MS4 permits. The Phase I MS4 permits include a requirement to provide water quality treatment for a specified level of previously untreated impervious surface. Each jurisdiction reports annually on permit compliance including the cumulative level of impervious restoration achieved.  The Phase II permits include a requirement to work toward treating a specified level of previously untreated impervious surface by 2025.  The following table provides the most recent information available on impervious surface restoration achievement by all Phase I and Phase II permitees.

Maryland’s upgrades to its largest Wastewater Treatment Plants (WWTP) are nearly complete with over 95% of the state’s wastewater facilities operating at ENR levels. However, significant challenges can occur at the most advanced wastewater treatement facilities and the recent maintenance and operational challenges at the State's largest wastewater facilities highlights this issue. Follow this  link  to see what MDE is doing at the Back River and Patapsco WWTPs.

Having invested over $1 Billion in ENR upgrades, the statewide average effluent concentration reached an all-time low of 2.9 milligrams of nitrogen per liter in 2020, surpassing the Phase III WIP performance target of 3.25 milligrams per liter, and nearly achieving our Climate goals. The current avg. concentration is 4.17 mg/l for 2021.

Over 400,000 households in Maryland use onsite disposal systems, commonly known as septic systems. The Phase III WIP focuses on two approaches for addressing these loads—upgrading conventional systems to Best Available Technology (BAT) and connecting systems to sewer. Sewer connections are particularly attractive, since they allow Maryland to make the best use of its ENR investments. Both upgrades and connections are paid for through the state’s Bay Restoration Fund, county, and private sources.

In 2019 and 2021, the number of septic systems in the model decreased through a disconnect in data reporting that excludes inspection dates in some of the locally provided data, this continues to be addressed by the State. 2020 Progress reflects part of that correction, but challenges still occur. It is anticipated that more systems will be captured in the 2022 annual progress assessment.