(AP) — Officials have issued health alerts for toxic blue-green algae at three lakes in eastern Nebraska.

The state Department of Health and Human Services says water samples at the lakes were above the Nebraska’s health alert threshold for a toxin released by certain strains of blue-green algae.

The lakes are Bluestem Lake in Lancaster County, Kirkman’s Cove in Richardson County and Willow Creek Lake in Pierce County.

A late August alert for Lake McConaughy near the Nebraska Panhandle has ended.

The alerts will continue at the lakes for at least two more weeks for additional testing.