SMITHVILLE, Mo. (AP) — Two beaches at Smithville lake have been closed because of an outbreak of blue-green algae.

WDAF-TV reports the U.S. Army Corps of Engineers and health officials made the decision to close parts of the lake 20 miles north of Kansas City.

The closure means no swimming will be allowed at Camp Branch and Little Platte, where the boat ramp and marina also will be closed.

The algae can be dangerous to humans and pets, causing nausea, vomiting, diarrhea, seizures, breathing problems and other unexplained illnesses.

Clay County sheriff’s dispatchers say the lake itself is not off-limits to boaters.

It’s not clear when the beaches will reopen.