ST. PAUL — Minnesota Department of Health officials are warning swimmers about harmful blue-green algae and high E. coli levels that have shown up in lakes across the state.

Conditions for algae and bacteria can be created by high temperatures and runoff from heavy summer rains. Trisha Robinson, supervisor of the waterborne diseases unit for the health department, says this is the time of year when waterborne diseases arise.

The St. Paul Pioneer Press reports that at least five beaches in the Twin Cities have briefly closed in the past month due to high levels of E. coli bacteria.

The Minnesota Pollution Control Agency issued a warning about blue-green algae last month after a boy was exposed to toxins while swimming in Alexandria’s Lake Henry in late June and was hospitalized.