County public health, Maryland Department of the Environment, and DC Water officials, speaking at a community forum May 18 in Glen Echo, were upbeat about the results of water quality testing in April and May. "E. coli levels have mostly met safe recreation standards since March 17, with brief spikes after rain," according to an MDE slide offered by Zachary Schafer, assistant secretary for policy. And Davis told the forum, "We are consistently reassured by the testing of the water…. The levels we can now safely say in the Potomac are the levels that you experienced recreating on it before. We feel very comfortable in that." (For the latest water quality results, see the D.C. Department of Energy & Environment data dashboard, Maryland Department of the Environment Potomac Interceptor Information page, and the Potomac Riverkeeper Network's spill data page.)
Schafer and Davis emphasized, though, that sediment testing methods and data interpretation are not well established, unlike the situation with longstanding water quality testing standards. MDE sampled sediment twice in April at 11 locations, including near Lock 10, Sycamore Island, Minnie's Island, and the Lock 6 Feeder Canal, with the result that e. coli and two other bacteria markers were found at "very, very low levels" except for Minnie's Island, just downstream from the contamination site, Schafer said.
The limited sediment testing so far, said Schafer, "paints a bit of a picture, but we don't know fully yet what that picture is telling us…. This is really the frontier of science." The uncertainty, he explained, stems from the lack of health-based standards for bacteria in sediment, the fact that "exposure pathways" are different (you might be walking in it, but you're not ingesting it), lack of standardized test methods, and the fact that data indicates presence of bacteria but not whether the bacteria are dead or alive. "Bottom line," one of his slides summarized: "Sediment data provides useful signals for investigation but cannot by itself determine public risk or confirm contamination source."
Davis agreed that with sediment testing, "We really are in new territory…. We don't have a lot of great data on risks associated with certain levels." There is no timeline indicating when the shoreline advisory might be reassessed. The county will be "following the data" and will "see where that takes us," she said.
Meanwhile, DC Water, which operates the Potomac Interceptor, has reported that removal of debris and contaminated material in the area tainted by the spill was completed in March, and full cleanup of the C&O Canal where sewage was temporarily directed during repairs is due to be completed in June.
DC Water has released its Emergency Repair and Rehabilitation Plan. A news release May 8 noted that under the plan, "further confirmation of water quality testing will continue daily through July 5 at the ten existing sampling sites and then transition to weekly testing through September 10…. In addition, the first phase of comprehensive environmental restoration efforts is expected to be substantially completed by late summer 2026."
The second phase of restoration, the release said, "is expected to be completed in the fall. This includes a comprehensive plan to replant native herbaceous species, shrubs, and trees, regrading temporarily impacted wetlands, and restoration of natural hydrology. Crews will also repair the C&O Canal's clay liner, add topsoil for the base and sides, and restore structural features."
CCA Chair Hugh Hilliard spoke at the Glen Echo meeting, pointing to the seeming conflict between Montgomery County maintaining a shoreline advisory and DC Water announcing that cleanup there is complete. "You say it's completed, but it must not be if we're still not able to use that area," Hugh said. DC Water representatives didn't respond to that comment, but MDE's Schafer said that ultimately, Maryland will require remediation and restoration to be comprehensive. The state, he said, will be looking for "return of the conditions we saw before."
CCA has been working with other interested groups collectively going by the name of CLEAR Potomac to assess the spill response and cleanup and to review DC Water's plans. This group is being led by the Potomac Conservancy and includes Potomac Riverkeeper Network, American Rivers, Sycamore Island Club, Minnie's Island, and others along with CCA. CLEAR Potomac representatives as well as residents near the spill site have expressed strong dissatisfaction with agencies' communications to the public and DC Water's plans going forward, including plans for preventing future catastrophic incidents.
Hugh submitted comments May 23 to DC Water and MDE on the April repair and rehabilitation plan, urging sediment testing at additional locations including the Little Falls takeout and along the canal. The submission noted that CCA has had discussions with MDE staff to clarify the locations where testing is needed.
The submission also sought commitment for further cleanup in the Lock 10 area as needed. "If there still is a health concern," CCA commented, "then additional cleanup and testing is needed … to restore the water and sediment quality to make it possible to lift the [county shoreline] health advisory. DC Water's job will not be complete until conditions have improved to a level sufficient to satisfy relevant health authorities that there is no need for a recreational health advisory."