Iowans requested a record number of nitrate test kits in 2025

• 2,223 kits were sent out nationwide, and over half of them went to Iowans, according to a recently released annual report by the environmental nonprofit. Last year, 1,060 kits were requested.
• Results sent in by volunteer participants showed nitrate readings were higher than average for the majority of 2025, per Wilson.

How it works: The league's Nitrate Watch program provides free test kits that help people measure nitrate levels in surface waters, such as rivers, lakes and streams, as well as drinking water.

• People who receive a kit are asked to send their results back to Izaak Walton, which helps record the nitrate levels of different water sources around the state.

The results: IWLA collected more than 4,000 readings from Iowa in 2025, including its citizen nitrate watch program, trained volunteer submissions and regular tests from agencies like Polk County Conservation.

• While the EPA's maximum nitrate allowance for drinking water is 10 mg/L, studies have shown that even 3 mg/L can contribute to health problems.
• Wilson said the number of high readings exceeding 5 mg/L in Iowa was higher than in past years.
• For example: Nitrate readings for source water near Yellow Banks Park reached 10 mg/L five times in 2025. In 2024, it only hit 10 mg/L once, and none in 2023.

By the numbers: Out of the 4,000 statewide readings in 2025, 40% of those were within 0–3 mg/L, and 18% were at 10 mg/L or above.

• For drinking water specifically, 52% were 0–3 mg/L and 5% were at 10 mg/L or above.
• The majority of the readings came from surface waters like the Raccoon and Des Moines rivers, which supply drinking water to much of central Iowa.

Zoom in: Daily average nitrate concentration levels hit 10 mg/L or greater for nearly 80 days last year.

What's next: While nitrate levels usually go down in the winter, Central Iowa Water Works turned on its filtering system in January due to high levels, which is a rare occurrence.

• "That may just be an aberration because of how mild this winter has been, but maybe it's also foreshadowing for what this year has to come," Wilson says.

How to request a kit: Though nitrate levels are lower in the winter, IWLA appreciates getting year-round results, Wilson says.

Residents can request a free kit here.