BLOOMINGTON, Ind. (AP) — Warmer weather brings people to lakes for swimming, boating and fishing, but Indiana officials are warning residents about the dangers of blue-green algae.

Limnologist Bill Jones studies inland waters. He told The Bloomington Herald Times that blue-green algae can produce a variety of toxic compounds. He says while most algae aren’t dangerous, blue-green algae can cause rashes, sickness and even death.

Blue-green algae can regulate buoyancy in water so the algae rise to the surface in warm weather in order to get sunlight.

“In the summer, it’s not uncommon to have blue-green algae as dominant in lakes,” Jones said.

Jones said to stay away from pond scum floating in bodies of water.

The Indiana Department of Environmental Management also recommends showering or bathing with warm, soapy water after spending time in reservoirs, lakes, rivers and streams.

Ken Severson with the Indiana State Department of Health said the department hasn’t confirmed human illness related to freshwater algal bloom in the past three years.

“However, the symptoms related to harmful algal blooms may appear as other commonly known ailments, so clinical staff may not be aware of symptoms related to algal bloom exposure,” he said in an email.

Much remains unknown about algae, Jones said. He said he hopes more research will be done on algae and that physicians and veterinarians will ask patients if they’ve recently been in lakes.

“Medical doctors need to be asking those questions,” he said.

Copyright 2017 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.