Utah reservoirs hit by five years of drought are struggling after an arid August.

Some reservoirs are close to empty, and others have dropped by upward of 20 percent according to federal data, the Deseret News reported.

Almost 60 percent of Utah is extremely dry, the U.S. Drought Monitor says.

Shallow water is causing health and safety warnings on some waterways. An algal bloom is growing in the low water at Utah Lake, and it spread to the Jordan River. Scofield Reservoir is closed, and Payson Lakes has also been affected.

The Utah Division of Parks and Recreation advised boaters to launch into the low water at Yuba Lake at their own risk.

Limited rain this year is compounding the usual summertime drop in reservoir levels, state parks official Ty Hunter said.

“This summer has been bleak on rain,” Hunter said. “We are starting to feel it in a couple of our reservoirs.”

Less than a quarter inch of rain fell in northern Utah last month, and an average of less than an inch of rain fell statewide.

Reservoir storage dropped 9 percent over the course of a month. Reservoirs that filled just over half their storage capacity toward the end of summer last year are now at 47 percent.

The U.S. Department of Agriculture Natural Resources Conservation Service released the report last week.