The state has issued a health alert for toxic blue-green algae for Pawnee Reservoir in Lancaster County, and an alert continues at Rockford Lake in Gage County, which was first placed on alert last week.

Samples taken earlier this week at the west beach of Pawnee Reservoir 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.) Samples taken at the east beach were well below the threshold. A reason for the difference in readings is because toxic algae tends to accumulate near the shorelines in the direction that the wind is blowing. However, since winds can shift direction and the toxins can likewise move, the alert is effective for all of Pawnee Reservoir.

Although levels were below the threshold at Rockford Lake 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 lake, 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 2009 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.)