State-issued health alerts for toxic blue-green algae have been issued for Merritt Reservoir (Cherry County) and Bluestem Lake (Lancaster County), and an alert continues in effect at Rockford Lake (Gage County). Kirkman's Cove Reservoir (Richardson County) was removed from the alert list this week.

Samples taken last week at the three listed 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). Kirkman’s Cove tested below the 20 ppb mark for the second consecutive week, and was removed from the list.

Lakes that are on health alert must have two consecutive weeks of readings below 20 ppb before the alert is removed.

Signs have been 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.)