PORTLAND, Ore. (KOIN) – Clark County Public Health issued a swim beach warning after elevated levels of E. coli bacteria were found in Battle Ground Lake during routine testing.

Officials warn the bacteria can cause serious gastrointestinal illness when the water is accidentally swallowed.

According to Clark County, test results for one of five samples collected at the lake on Monday showed elevated levels of the bacteria, while the other samples shows bacteria levels within acceptable water quality standards.

Health officials warn against swimming and wading in the water and advise those who have had contact with the water to rinse off after.

Clark County will test the water again on Tuesday, June 21. Depending on those test results, the county may lift the warning or close the beach.

In the meantime, Battle Ground Lake State Park is still open to the public. Officials noted while fishing is permitted, all fish should be thoroughly cleaned before consumption. All fishing gear should be cleaned as well.

This comes as an E. coli warning was issued for Vancouver Lake on June 10. Health officials are also monitoring a “harmful” algae bloom but said toxin levels haven’t reached high enough to warrant an advisory.