Iowa DNR photo

It’s the hottest week of the year so far and some Iowans are finding “No Swimming” signs posted on their nearby beaches, thwarting hopes of cooling off with a dip.

One such body of water is Green Valley Lake at Green Valley State Park just north of Creston. Amanda Husband, an environmental health specialist in Union County, says there’s no swimming at the lake until further notice.

“Fishing would be fine,” Husband says. “We just advise folks to make sure they’re cleaning their fish of all of their guts and stuff with clean water and are then cooking them to the proper temperature.”

The problem is known as microcystin toxin, which is a byproduct of blue-green algae.

Husband says, “Some lakes are really nutrient-rich lakes and that causes the algae to make blooms and those blooms can give off toxins and those toxins are what we test for to advise folks not to swim.”

Coincidentally, the hot weather that prompts many of us to head for the water is exactly the reason why we can’t go swimming.

“I would expect the problem will persist until we have cooler temperatures and some rain,” Husband says. “If it’s any indication as in previous years, we could see this problem all throughout late summer and into early fall.” That toxin can be just as dangerous for pets as it is for people.

“There is a walking trail around there and if pets get that algae on their paws and on their coats, if they lick that algae off, they can get a really high concentration of it and it can be deadly to their pets,” she says.

Check the Iowa Department of Natural Resources website for details on the waterways near you.