WALLA WALLA - Health officials are warning not to swim in Bennington Lake after moderately high E. coli samples were discovered there Thursday.
That same day tests revealed the high levels, officials with the Walla Walla District of U.S. Army Corps of Engineers put up signs around the lake warning people not to swim in or drink from the lake.
Lower water flows which have created a more stagnant aquatic environment is one possibly reasons for the high levels of E. coli, an official said.
The state threshold for E. coli in a body of water is 126 parts per 100 milliliters; Bennington Lake had a measurement of 175 parts per 100 milliliters.
On Friday, Corps officials took several tests around the lake and expect results back on Monday.
If the tests come back negative, the signs will be removed, but if the high levels continue, officials will try to find a possible source to the contamination.
Boat launching and fishing are still permitted at the lake, but officials warn lake users to use good hygiene, wash hands thoroughly and be careful with splashing water.