BEATRICE, Neb. (AP) — Nebraska health officials say three lakes are on health alerts because of toxic blue-green algae blooms.

The lakes are Iron Horse Trail Lake in Pawnee County, Rockford Lake in Gage County and Willow Creek Reservoir in Pierce County.

Testing by the Nebraska Department of Environmental Quality this week showed the lakes have high levels of toxin. Skin exposed to the toxin can develop rashes and blisters, and drinking tainted water could cause headaches, nausea and muscle pain.

Signs are posted advising the public to use caution, and designated swimming beaches are closed. Recreational boating and fishing are permitted, but the public is warned to use caution and avoid exposure to the water.

Health alerts are lifted when toxin levels are below advisory concentration for two consecutive weeks.