Canoers paddle the lake at Union Grove State Park near Gladbrook last July. The lake is currently (as of Tuesday, May 30) under a swimming advisory due to high bacteria levels. PHOTO BY RUBY F. MCALLISTER

The Iowa Department of Natural Resources issued swimming warnings for three state parks ahead of the Memorial Day weekend in its first beach report of the year.

Due to high bacteria levels, the department does not recommend swimming at Union Grove State Park in Tama County, Lake Keomah State Park in Mahaska County, and the south lake of Pine Lake State Park in Hardin County.

The beach water at all three has a history of higher-than-safe bacteria counts, and recent tests show they exceed a DNR safety limit for swimming.

Union Grove had a bacteria concentration nearly 25 times the safety threshold, whereas the other two were less than twice the threshold.

Bacteria counts can change significantly over the course of days.

For more information, visit the Iowa DNR’s Beach Monitoring website: https://programs.iowadnr.gov/aquia/Programs/Beaches

For current beach advisory status, call the DNR beach monitoring hotline at 515-725-3434.