The recent rains and flooding have carried a lot of material into the lakes and rivers in the state. Mary Skopec with the Iowa Department of Natural Resources beach monitoring program says the influx of water shows up in testing. “The rainfall that we’ve had certainly has an impact in the immediate days right after that rainfall. We do see high levels of sediment and dirt running off the farm fields, so we do see a spike in those bacteria levels immediately following,” Skopec says.
But the bacteria spike doesn’t last long. “When we have a couple of really dry days like we’ve had, and some sunny weather, the levels of bacteria seem to drop pretty dramatically,”Skopec says. She says there are some exceptions. “If you’ve got a lake that has a flooding situation and the sediment is suspended in the water longer, you may see those the levels stay elevated for a week or two weeks. But most or our lakes we see the levels come down within a day or two,” Skopec says. “And we are actually resampling some of our lakes to see if the high levels that we experienced on Monday and Tuesday are coming down now on Wednesday and Thursday.”
The flooding carries other things like trees into the water, and Skopec says it’s not as much an issue in lakes as the debris tends to fall to the bottom of the lake, but is more of an issue in rivers. “If people plan on being out on boats or kayaks this weekend, they want to be aware of that kind of thing, debris up against bridges or just general debris,” Skopec says.
You can go to the DNR’s website to find out if there are bacteria issues at your favorite state beach or call the beach hotline at: 515-725-3434. The DNR begins testing the water weekly at all state park beaches, and at participating city and county beaches at least once per week on Memorial Day, and continues the testing through Labor Day.