If you're planning to swim at the Oregon Coast, avoid Cannon Beach for the next few days.

The Oregon Health Authority today issued an advisory, warning people not to splash into Cannon Beach ocean water, which is currently full of "higher-than-normal levels of fecal bacteria." Contact with contaminated water can lead to stomach cramps, skin rashes, upper respiratory infections and diarrhea. Children and elderly people are particularly vulnerable.

This is the second fecal bacteria advisory issued since Memorial Day, says Tara Chetock, OHA's program coordinator. The agency doesn't know exactly what the cause is. Since 2016, 19 fecal bacteria advisories have been issued at the Oregon Coast.

Chetcok says the reasons for the contamination vary, and because the agency tests for a type of bacteria found in any warm blooded animal, it "can't differentiate whether it's from humans or animals."

"We often don't have a concrete answer for what causes contamination," Chetock says. "It can be a variety of reasons, including run-off from streams, animal activity and failing septic systems."

OHA cautioned visitors in today's advisory to "avoid wading in nearby creeks, pools of water on the beach, or in discolored water, and stay clear of water runoff flowing into the ocean."

"Even if there is no advisory in effect," it continued, "officials recommend avoiding swimming in the ocean within 48 hours after a rainstorm."

Cannon Beach is still open to other activities, and nearby coasts are not affected.

Chetock doesn't have a prediction for when the beach will reopen to swimming. She says OHA will continue collecting samples until the fecal bacteria levels drop to an acceptable level.