State-issued health alerts for toxic blue-green algae continue in effect at Rockford Lake (Gage County) and Kirkman's Cove Reservoir (Richardson County) joined the health alert list this week.

Samples taken earlier this week at both lakes 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). Rockford Lake tested below the limit last week after having been listed the previous week, but tested high again this week.

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 beaches at the lakes will remain closed during the health alert. The public is advised to avoid activities that could involve accidental ingestion of water, and to make sure their pets don’t drink from the lake. People can still use the public areas for picnics and other outdoor activities.

The state will continue to conduct weekly sampling at 47 recreational lakes through September. Monitoring will end for the year after the September 29 sample. Sampling results for toxic algae and bacteria will be updated every Friday and posted on NDEQ’s web site, 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.)