Work continues on the Potomac Interceptor, a section of which collapsed on January 19, along Clara Barton Parkway and the I-495 interchange and C & O Canal Historical Park causing a sanitary sewer overflow. 

A bypass system established five days after the overflow occurred continues to successfully divert wastewater around the collapse site and back into the Potomac Interceptor further downstream. 

However, late this evening a limited overflow occurred at the site but wastewater did not reach the Potomac River. An estimated 3600 gallons overflowed and was captured by site containment measures and pumped back into the sewer system. These overflows are primarily due to increased wastewater flow associated with snowmelt and brief pump maintenance and operational issues. 

Until full functionality is restored to the Potomac Interceptor, there remains a residual risk of additional limited overflows.

Daily water quality testing continues. Sampling results at downstream sampling locations continue to remain within EPA standards for acceptable levels.

Water Quality Sampling Results

Historical data indicate typical levels in the Potomac River can range from 10 to 5,000 MPN/100mL. Variability in E. coli results are common and are influenced by multiple factors, such as weather and subwatershed activities and conditions, including aging sewer infrastructure and illicit discharges.