Why Iowa Water Quality Progress Looks Different Than We Expected

By: Hertz Stewardship Committee and the Iowa Ag Water Alliance

If you’ve been following news in Iowa lately, you may have seen some concerning headlines about nitrate levels in our water supply.

We wanted to provide a grounded, unbiased overview of why drinking water sources have high nitrate levels right now, and how you – as a landowner – can have a positive impact on water quality.

Drought, Then Rain: A Perfect Storm for Nitrates

Nitrate loss in farm fields is impacted by both farming practices and weather patterns like drought and heavy rain.

Iowa endured nearly four years of drought that finally broke heading into 2024 and 2025. Here’s what happened during that drought.

• Without rain to flush nitrate from the system, it built up in the soil.
• Nitrate was also stored in the water table below tile lines.
• Most nitrogen was applied at typical rates, contributing to additional build-up.

During those dry years, nitrate levels in water were lower, which had less to do with implementing conservation practices and more to do with a lack of water flow.

On the flip side, when rain started falling again, high nitrate levels in water were directly related to higher flow. Heavy rains carried all the stored nitrate in the soil and water table to drinking water sources downstream.

Weather patterns exacerbate nitrate issues in Iowa, but it doesn’t mean farmers can’t make a difference in improving water quality.

Where Targeted Efforts Are Making a Measurable Difference

The reality of watershed work is that it takes a lot of acres and practices before you start seeing meaningful differences in water sample nitrate levels. The good news is that water samples are seeing progress in sub-watersheds.

Sub-watersheds are about 4,000 acres, and when watershed experts target conservation practices in those areas, the impact is more immediately measured.

Black Hawk Lake in northwest Iowa is an example of where farmers and landowners are making a huge difference in water quality. Since 2012, farmers have installed 90,000 feet of terraces and grassed waterways, 79 acres of filter strips, 49 acres in wetlands, plus increased acres utilizing cover crops and reduced tillage.

Iowa State University found that on average, sub-watersheds in the Black Hawk Lake area with high conservation adoption had 64% less nitrogen export than sub-watersheds with low conservation. Microcystin levels in the lake (caused by algae that feed on nitrogen) dramatically dropped off around 2016. Beach recreation warnings due to toxic algae were almost nonexistent by 2017. Why Iowa Water Quality Progress Looks Different Than We Expected Hertz Stewardship Committee and the Iowa Ag Water Alliance

Your Farm, Your Role

Farmers and landowners can’t control the weather — but they can control what happens on their land. Cover crops, optimized nitrogen timing, bioreactors, saturated buffers, and wetlands are all proven tools that reduce the amount of nitrate leaving fields. Recently, Hertz Farm Management partnered with Heartland Cooperative to implement edge-of-field practices like saturated buffers and bioreactors on managed farms. More to come on that in our next Ag Update.

At Hertz Farm Management, we believe the landowners and farmers we work with are part of the solution. That’s why we donate to and partner with organizations like the Iowa Agriculture Water Alliance (IAWA) to increase onfarm conservation. Their mission is to increase the pace and scale of farmer-led efforts to improve water quality.

IAWA has a tool called the Conservation Compass that helps farmers and landowners find cost-share to help pay for conservation.

If you’re interested in learning more about conservation practices that could work on your farm — and programs that can help offset the cost — talk with a Hertz Farmland Professional. The water flowing from your land is part of your legacy. And the good news is that you have more influence over it than the weather headlines suggest.