DES MOINES, Iowa — The lawn watering ban is still in effect going into the holiday weekend. Central Iowa Water Works said they need to see a sustained downward trend in nitrate before that can be lifted.

In the latest testing on Wednesday afternoon, the Raccoon River is at 16.04 mg/L and the Des Moines River is 12.36 mg/L. The Fleur Drive Treatment Plant is 7.41 mg/L, while the McMullen plant is 7.57 mg/L.

The U.S. Environmental Protection Agency set the standard that nitrate should not be over 10 mg/L. So, Des Moines water is considered safe. But safe is subjective to some scientists. 

In the Polk County water research report released Tuesday, it stated that some groups in their research have 5 mg/L as an acceptable nitrate threshold. In that research, a lot of those lower acceptable numbers come from research on cancer. 

Claire Hruby, an environmental science professor at Drake University, was one of the scientists on the Polk County water report, and she says some research shows there is a risk of certain cancers even when the nitrate is above 3 mg/L.

“Most of the research, especially cancer, is a long-term chronic problem. So, you have to be drinking high-nitrate water for a while. Something like birth defects is a short window,” Hruby said. ” I think our goal should be a lower number. But I’m also realistic. A lower number would put most of our small towns out of business.”

Even though the water is considered safe by EPA standards, she’s taking her own precautions for her and her family. 

“As a mom, I worry. I read all these health effects papers. Personally, I have an under-counter reverse osmosis system,” she said. “I love the folks at Des Moines Water Works. I know they’re meeting the standard. I know the water is safe, but safe is subjective. It takes a while for the regulations to catch up with the science… That’s the uncomfortable part of this conversation, right? That maybe we should be doing better. We don’t know for sure. We need to start acting on the science that we do have, even if it’s not conclusive.”

The last few weeks has sparked a lot of curiosity. Many people are ordering at-home water tests. But how accurate are those? 

“I recommend if you’re really serious about wanting to know a precise number that you order a test kit that’s going to go to a certified laboratory,” Hruby said. “But for your own curiosity, if you want to use these test strips, the colors are a little bit hard to tell apart, but you can tell if you’re at zero or if you’re at ten.”

Those who use the test strips should ensure they are reading them correctly.

“The biggest thing that folks have been misunderstanding on the strips that they’ve been using is the difference between nitrate and nitrate as nitrogen. Nitrates is a molecule. It’s got nitrogen and oxygen. If we measure the whole molecule, we get a different mass, a different way than if we measure just the nitrogen. The nitrate, as N is measuring just the nitrogen. And that’s where we get the 10 mg/L standard.”