The state is warning people not to swim or drink water from Big Indian Creek Lake in southeast Nebraska.
The warning at the Gage County lake followed water sampling that showed a high level of microcystin, a toxin released by strains of blue-green algae.
Skin exposed to the toxin can develop rashes and blisters. Someone who drinks water containing the toxin is at risk for headaches, nausea and muscular pain.
The state samples water at 49 public lakes every week. Big Indian Creek Lake was the only spot with a high reading.
Sampling of the state lakes will end for the year next week.