• DC Water, in coordination with the Environmental Protection Agency, is evaluating soil samples from areas directly impacted by the Potomac Interceptor overflows, where the initial clean-up is complete. This includes the drainage channel along Clara Barton Parkway, Rock Run Culvert (Culvert 12), and the unnamed tributary to the Potomac River. 
• Clean-up continues to remove sludge and debris from the C & O Canal between locks 10 and 13. 
• With initial clean-up and sludge removal complete between locks 13 and 14, crews are constructing access to the C & O Canal. This access will allow heavy equipment to reach and remove contaminated soil from the canal without using the towpath. 
• DC Water met with the National Park Service to evaluate the historic locks and determine the best strategy for cleaning and restoration. As there is no established precedent for this type of work, DC Water is developing a specialized plan to clean the walls and lock mechanisms. 
• Over the next week, DC Water and its contractor will begin mobilizing for the accelerated long-term rehabilitation project that had been previously planned, covering more than 2,700 linear feet of the interceptor in this area. 
• In preparation for slip lining—which involves inserting new pipe sections into the existing pipe—a third site will be excavated along Clara Barton Parkway outside the I-495 Beltway. Construction will include installing trench boxes with supportive excavation to access the interceptor for rehabilitation. 
• Long-term rehabilitation requires using multiple locations to insert new pipe sections due to several vertical drops along the pipeline. Slip lining is intended for long, straight sections and is not used where vertical drops occur; geopolymer is applied instead. 

Water Quality Sampling Results 

It's important to understand that rain, snow, heat, contaminated runoff, and natural sources of E. coli such as wildlife can cause higher bacteria levels in urban rivers such as the Potomac River. For this reason, experts recommend avoiding the water for at least 48-72 hours after heavy rain. This is reflected in the wide fluctuations seen during heavy rainfall last week and that have since fallen back within the typical range for recreation.  

As there have been no overflows to the river from the Potomac Interceptor for more than a month prior to completion of emergency repairs, fluctuations in measurements are more likely due to these other known factors. 

For the Potomac River, historical water quality data shows E. coli levels may vary from a range as low as 10 MPN/100mL to as much as 5,000 MPN/100mL on a given day. A more detailed explanation is posted on the District Department of Energy and Environment (DOEE) website at doee.dc.gov/release/potomac-interceptor-update-and-faqs. 

Sample results from March 16 - present. Past results may be found here. 

For the latest updates and information, including how to provide feedback on the environmental rehabilitation, go to our dedicated Potomac Interceptor Response page.