Another round of water tests completed Thursday could not identify the substance that spilled into the Anacostia River Monday, but the tests showed that the substance was not petroleum, the Coast Guard said.
Based on the test results, Lt. Cmdr. Randall Brown of the Coast Guard reiterated that the material didn't pose an imminent danger.
"Assessments of the area continued today, and there have been no reports of negative impact to wildlife or vegetation. Several samples from the river and shoreside locations are being analyzed in a lab," Brown said.
The waterway is open to boaters, and there are no reports of impact to the public or wildlife.
Residents can report new information in regards to the incident to the National Response Center at 800-424-8802.