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Hundreds of wastewater treatment facilities throughout the Chesapeake Bay watershed are being upgraded with advanced technology to reduce the amount of nutrients that are discharged into the Bay's tributaries. Wastewater treatment plant upgrades account for a large portion of overall estimated nutrient reductions to date, and Bay jurisdictions are relying on additional reductions from wastewater to achieve about 15 percent of total overall nutrient reduction goals.

Chesapeake Bay Program Goal to Reduce Nutrients in Wastewater

Since 1985, the Chesapeake Bay Program has been working towards a goal to reduce nutrient pollution from wastewater facilities to correct nutrient-related problems in the Bay and its tidal tributaries by 2010. As of 2015, the seven Bay jurisdictions – Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia – have effectively met the goals to reduce nitrogen and phosphorus from wastewater.

Using Technology to Reduce Nutrients in Wastewater

In 2005, Chesapeake Bay jurisdictions began to implement a new permitting process that limited the amount of nitrogen and phosphorus that the Bay watershed's 483 significant wastewater treatment plants could discharge. To meet the nutrient limits, most of these facilities are being upgraded with nutrient reduction technology, including biological nutrient removal (BNR) and enhanced nutrient removal (ENR).

  • Biological nutrient removal (BNR) uses microorganisms to remove nitrogen and phosphorus from wastewater during treatment. It consists of three steps: an anaerobic step called enhanced biological phosphorus removal; an aerobic step called nitrification; and an anoxic step called denitrification. Wastewater treated at facilities using BNR contains less than 8 milligrams per liter (mg/l) of nitrogen.
  • Enhanced nutrient removal (ENR), which is being used in Maryland, improves upon the nutrient reductions achieved through BNR. Wastewater treated at facilities using ENR contains 3 mg/l of nitrogen and 0.3 mg/l of phosphorus. Maryland's Bay Restoration Fund – also known as the "Flush Fee" – funds ENR upgrades for the state's 66 major wastewater treatment plants that discharge to the Bay.

Some states, including Pennsylvania and Virginia, have created nutrient trading programs that encourage wastewater treatment plants to design upgrades with greater nutrient reductions, then sell nutrient credits to other facilities. Well-designed nutrient trading programs can be beneficial because they provide cost-effective solutions for some treatment facilities that need to meet stricter nutrient limits.

Legislation to Reduce Phosphates in Wastewater

Technology upgrades are not the only way Chesapeake Bay jurisdictions are reducing nutrients in wastewater. Several laws have been passed that set strict limits on the amount of phosphorus in consumer cleaning products, including laundry and dishwasher detergents, to slow the flow of phosphates coming from Bay watershed homes.

  • In the 1980s, five of the Bay jurisdictions (Maryland, New York, Pennsylvania, Virginia and the District of Columbia) banned laundry detergents containing phosphates. This move reduced the amount of phosphorus flowing to the watershed's wastewater treatment facilities by 25 to 30 percent, or an estimated 7.5 million pounds annually.
  • Maryland, New York, Pennsylvania and Virginia have recently passed bills to ban dishwasher detergents containing phosphorus. The phosphate dish detergent bans, which will go into effect in July 2010, will remove an estimated 52,000 pounds of phosphorus that is currently being discharged from treatment facilities.



Chesapeake Bay News

In The Headlines

Bay 101: Wastewater Treatment Plants

February 04, 2011

Old wastewater treatment plants can contribute nitrogen and phosphorous to the Chesapeake Bay, but plants across the watershed are being upgraded. Alan Quimby from the Queen Anne’s County (Md.) Department of Public Works explains how these upgrades will help the Bay.


New Insights: Science-based evidence of water quality improvements, challenges, and opportunities in the Chesapeake (Executive Summary)

Publication date: February 19, 2014 | Type of document: Report | Download: Electronic Version

New Insights: Science-based evidence of water quality improvements, challenges and opportunities in the Chesapeake compiles data collected and analyzed by Chesapeake Bay Program partners, including the University of Maryland Center for…

Evaluation of Wastewater Treatment Plants for BNR Retrofits Using Advances in Technology

Publication date: May 01, 1999 | Type of document: Report | Download: Electronic Version

This project was initiated on June 1, 1995 for the purpose of stimulating efforts towards the reduction of point source nutrient discharges to the waters of the Chesapeake Bay Water. The primary emphasis of the BNR retrofit recommendations…

Water Quality GIT BMP Review Protocol

Publication date: | Type of document: Policy Document | Download: Electronic Version

July 13, 2015 version.

From Around the Web

Bay FAQs

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Bay Terms

  • Anoxia
  • Biological nutrient removal (BNR)
  • Chemical contaminants
  • Denitrification
  • Enhanced nutrient removal (ENR)
  • Nitrification
  • Nutrient removal technology (NRT)
  • Nutrients
  • Pollution
  • Tributary


Bay-Friendly Tips

  • Keep Sewage On Board
  • Keep sewage on board your boat in a portable toilet or holding tank. Dispose of it only at an approved pump-out facility.
  • Use Toxic-Free Personal Products
  • Use eco-friendly lotions, cosmetics and perfumes to keep toxic chemicals from washing off of our bodies and into our waterways.
  • Use Toxic-Free Cleaning Products
  • Use eco-friendly cleaning products to keep toxic chemicals out of our waterways. Plain soap and water can rid surfaces of bacteria and are safer for our water supply.
  • Compost Kitchen Scraps
  • Instead of throwing kitchen scraps down the garbage disposal, compost them to create a rich soil for potted and in-ground plants.
  • Dispose of Medicine Properly
  • To keep medicine out of our waterways, don't pour expired or leftover drugs down the sink or flush them down the toilet. Instead, return unused medicine to a consumer drug return location or foul your medication with coffee grounds or cat litter and put it in the trash.
  • Keep Your Drain Fat-Free
  • Don't pour fat, oil or grease down your drain, where they can clog pipes and lead to sewage overflows over time.
  • Take Shorter Showers
  • Take shorter showers. By cutting your shower time by five minutes, you can save 10 to 12 gallons of water per shower.


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