POLK COUNTY, Fla. (WFLA) – Memorial Day weekend plans may be thwarted by a summertime menace to Florida waters known as blue-green algae blooms.

The Florida Department of Environmental Protection (DEP) detected the harmful blue-green algal toxins on the east side of Lake Hamilton by Sample Park on May 17.

Health officials warn people to stay away.

“They should not be in the water, including boating, anything like that. Shouldn’t have pets around the water either because they could get sick,” said Pamela Acosta-Torres, spokesperson for the Florida Department of Health in Polk County.

Boating can cause the water to mist and enter the lungs, causing irritation.

Other exposure can cause rashes and stomach problems.

“Blue-green algae is something that’s natural in Florida’s fresh water sources, but at certain points, it can be aggravated, and they can start producing that toxin. It’s worse when it’s sunny, when it’s hot outside,” said Acosta-Torres.

According to a DEP spokesperson, aerial imagery showed potential bloom development in April but no microcystin toxins were detected from that sample.

DEP re-sampled from the site on May 17, and a trace level was detected.

“If microcystin toxins are detected, regardless of the level, a health advisory will be issued,” wrote a spokesperson in a statement.

Tammy Downs, who operates the nearby Kevin’s Bait and Tackle, said she will let Memorial Day customers know about the risk.

“I think people’s health would be more important, so I would rather tell them and not worry about that, business-wise,” she said.

She noted people have hundreds of lakes to visit in Polk County this holiday weekend.

Report symptoms from exposure to a harmful algal bloom or any aquatic toxin to the Florida Poison Information Center. Call 1-800-222-1222 to speak to a poison specialist immediately.