The state has issued a health alert for toxic blue-green algae at Johnson Lake in Gosper County, and an alert continues at Swan Creek Lake 5A near Tobias in Saline County, which was first placed on alert last week.

Samples taken earlier this week at Johnson Lake were above the state’s health alert threshold of 20 parts per billion (ppb) of total Microcystins (a toxin released by certain strains of blue-green algae.) Although levels were below the threshold at Swan Creek Lake 5A this week, a health alert remains in effect. Lakes that are on health alert must have two consecutive weeks of readings below 20 ppb before the alert is removed.

Signs are being posted to advise the public to use caution, and the swimming beach at the lakes will remain closed during the health alert. Recreational boating and fishing are permitted at the lakes, but the public is advised to avoid activities that could involve accidental ingestion of water. People can still use the public areas for camping, picnics and other outdoor activities.

The lakes will continue to be monitored weekly throughout the 2010 recreational season. Sampling results for toxic algae and bacteria will be updated every Friday and posted on NDEQ’s web site, https://dee.nebraska.gov/home.

(For more information about potential health effects of toxic blue-green algae, what to look for, and steps to avoid exposure, please refer to the Toxic Algae Fact Sheet.)