BEATRICE, Neb. (AP) — State health and environment officials have issued a health alert for toxic blue-green algae in Rockford Lake near Beatrice in southeastern Nebraska.

The alert was issued following tests on the lake’s water earlier this week. Signs have been posted at the lake urging people not to swim there.

Officials say the alert will continue for at least two more weeks. People can still use the lake’s public areas for camping, picnics and other outdoor activities.

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.