Stay out of the St. Lucie River at Leighton Park in Palm City and the Roosevelt Bridge in Stuart because of bacteria, the Florida Department of Health warned Friday.

Water samples taken at the sites Monday and Wednesday showed higher-than-normal levels of enteric bacteria, an indication of fecal pollution.

Potential health risks for those who ingest or come in contact with the water include upset stomach, diarrhea, eye irritation and skin rashes.

How bad is it?

The health department considers levels above 70 enteric bacteria colonies in a 100-milliliter water sample to be unsafe. Monday's samples had bacteria levels of:

Leighton Park: 624

624 Roosevelt Bridge: 111

Because of the high bacterial levels, the two sites were sampled again Wednesday, and the results were still in the high range:

Leighton Park: 164

164 Roosevelt Bridge: 137

Samples taken at Sandsprit Park near Port Salerno and the Stuart sandbar in the Indian River Lagoon between Sewall's Point and Sailfish Point each registered 53 colonies per 100 milliliter, which is in the moderate level.

The high-level areas will be tested again Monday. The advisories will remain in effect until results show consistent readings in the good range.

What causes it?

The bacteria typically gets in waterways when heavy rains — like those in the area since Sunday — wash fecal matter from pets, livestock and wildlife into the water.

"That's exactly our theory about what happened," said Health Department spokeswoman Renay Rouse. "We had all that rain that started Saturday, and it rained all day Sunday. All that stuff with bacteria on the land washed into the water."

More: Record rains falls on Treasure Coast

Leaky septic systems and sewage lines also can cause the bacteria to enter waterways.

More: Stay out of the water at 3 beaches in Vero Beach

A similar warning was issued Thursday at three ocean beaches in Vero Beach: Sexton Plaza, Humiston Park and South Beach.

Florida Healthy Beaches

The Health Department samples water every week along the St. Lucie River. Martin County beach sites are sampled every other week.

How's the water?: Check on the status of the water near you with our interactive map. Note: The map will not reflect the new advisories until an auto-update at 5 p.m.