Removing Nitrogen from Wastewater Protects our Waterways

Nitrogen natural element found in the earth and in our atmosphere. It is a vital component of life for many organisms, but too much nitrogen in our waterways can be harmful. Excess nitrogen can cause algal blooms which deplete the oxygen that fish and other aquatic life need to survive.

For many years, DC Water has been a leader in voluntarily reducing nitrogen and phosphorus discharge from the wastewater treatment process. We have an ongoing and aggressive program to reduce nitrogen levels discharged from our Blue Plains Advanced Wastewater Treatment Plant into the Potomac River, a tributary of the Chesapeake Bay.

DC Water operates under an NPDES permit issued by the EPA. This permit sets limits for the amount of nitrogen and phosphorus that can be discharged from the treatment plant.

NPDES Permit

NPDES Permit Fact Sheet

DC Water began operating a full-plant Biological Nitrogen Removal (BNR) system in 2001 to maintain compliance with our EPA permit. At that time the treated wastewater that was discharged, or effluent, could not contain more than 7.5 mg/l total nitrogen on an annual average basis. In 2015, DC Water brought our Enhanced Nitrogen Removal Facilities (ENRF) online to meet a new effluent limit of 4.0 mg/L of total nitrogen on an annual basis. With this advanced system, DC Water has not only met, but exceeded, our required reduction of nitrogen. Since the implementation of our nitrogen removal facilities, DC water has prevented over 144 million pounds of nitrogen from entering the Potomac River.

To learn more about nitrogen removal at Blue Plains, please review our  Blue Plains Advanced Wastewater Treatment Plant brochure.

Upcoming Meeting

Board of Directors Meeting

April 24, 2023

Monday 9:00 AM

Announcement

Aerial View of Construction near Watergate Complex Shows cranes and construction of drop shaft underway
Scaffolding Installation Begins near Watergate Complex for Potomac River Tunnel Project

Rock Creek and Potomac Parkway NW Beginning September 23, 2025, to Mid-November 2025

DC Water is installing temporary scaffolding at the Rock Creek Trail site, west of the Watergate Complex. Trail users are advised to adhere to flagger instructions during installation.

Scaffolding installation is expected to be completed by September 26, 2025, and will remain in place until mid-November 2025.

Latest Blog Post
A helicopter lowers a drill rig to workers on the Potomac River.
DC Water begins drilling in Potomac River to explore options to rehab underwater sewer line
When one of your major sewer lines runs through the Potomac River, a backhoe and trencher won't do. That's why we've got helicopters carrying a 14-ton drill and workers suspended midair over the Potomac.
Upcoming Meeting
Date
October 7, 2025
Tuesday, 9:30 AM

Upcoming Events

Sep 27
11:00 am - 7:00 pm
Sep 28
10:00 am - 2:00 pm
Sep 29
6:30 pm - 8:00 pm

Customer Service Center Announcement

Payment Plan Incentive: provides a credit back of 40% of the last 3 payments made and in the new fiscal year 50% will be credited. Eligible participants are residential customers who have had an outstanding balance for 60 days or greater and with an outstanding balance of $500 or more.