A secondary water assessment showed no signs of oil in the substance found in the Anacostia River earlier this week.
Initial tests indicated a presence of a petroleum-based substance in the Anacostia River, but when the U.S. Coast Guard followed up with a water assessment on Tuesday, they found no oil.
The District's director of the Department of the Environment Christophe Tulou says they believe the cause may now be related to heavy rains and dust or silt that seeped into the river after Sunday evening’s heavy rainstorms.
The substances collected earlier in the week are currently being tested in two labs. The results are expected back as soon as today.