People living in central Iowa received a wake-up call last week that should drag water-quality back in front of the state’s 3.2 million residents.

Iowa’s largest water supplier, one serving a fifth of the state’s homes and businesses, ordered its 600,000 customers to immediately reduce water demand by ending lawn-watering and cutting use in other ways.

Such orders typically come during persistent drought when water supplies are short. This time, water is plentiful. But Central Iowa Water Works is struggling to remove enough nitrates to make its water safe for human consumption.

This is not just a Des Moines area problem. This is an all-of-Iowa problem.

While fertilizing lawns and golf courses in urban areas contributes to the nitrate problem, the primary reason, by far, for elevated levels of nitrates is excess application of commercial nitrogen fertilizer and manure on farm ground.

This focus on nitrates in drinking water is not some arcane concern motivated by fans of lush lawns. The heart of the issue is public health.

Nitrates are of special concern for infants under 6 months of age and pregnant women. Studies also suggest even nitrate levels below the federal safe-drinking-water standard could contribute to an increase in colon and rectal cancers, thyroid disease and some birth defects.

Statistics from Central Iowa Water Works illustrate the scope of the current problem: Federal regulations limit nitrates in public water supplies to no more than 10 milligrams per liter (mg/l). Nitrates in the “finished water” last week were at 9.8 mg/l after passing through the utility’s treatment plant.

Nitrates in the Raccoon River’s untreated water edged over 20 mg/l, the highest since a record of 24.39 milligrams was set in 2013, utility officials said. Nitrates in the Des Moines River last week stood at 17.15 mg/l.

Des Moines has operated a sophisticated nitrate-removal system, one of the world’s largest, since 1992. The system is used when nitrate levels jeopardize the utility’s ability to comply with federal water standards.

The system has run at capacity this spring for more than 50 consecutive days. The utility cannot keep up with customer demand because of the high nitrate levels in water entering the treatment plant.

There is no mystery what needs to be done. The “how” is contentious.

The mandatory water conservation steps announced last week put the spotlight on the chief cause of those high nitrate levels — agricultural runoff carrying nitrates from farm fields into Iowa’s streams, rivers and lakes.

Therein is the nub of the issue.

Scientists and politicians developed the Iowa government’s plan for dealing with elevated levels of nitrates and phosphorus — called the nutrient reduction strategy — a dozen years ago. The plan is strictly voluntary, and improvement has been negligible.

Ted Corrigan, general manager of the Des Moines Water Works, told Iowa Capital Dispatch in 2022 after a progress report came out: “The real solution is upstream. The landowners there are the solution-holders. They have the ability to make changes to the way they use their land in order to keep nutrients on the land and in the soil, where they belong.”

There is more to this issue than lawn esthetics, the hours city “splash pads” operate, and the ability to wash cars whenever drivers want.

High nitrate levels affect every Iowan, regardless of where they live. They pay more for tap water, and evidence suggests they may pay with their health, too. The latest report by the Iowa Cancer Registry shows Iowa is one of two states nationally with rising rates of new cancers cases.

Sarah Green, executive director of the Iowa Environmental Council, a nonprofit group, said recently, “We know that our environment and our health are inextricably linked. With so many Iowans’ lives touched by cancer, it’s important that we explore every link and find ways we can work together to mitigate all potential sources of risk and save lives.”

Environmental groups criticize the nutrient reduction strategy as a solution that relies on “magical thinking.”

An Environmental Working Group study in 2021 found that three-fourths of the data showing high nitrate and phosphorus levels in rivers and lakes were in counties where at least 70 percent of cropland is fertilized.

That year, Iowa Capital Dispatch looked at the environmental group’s data for Hardin County in north central Iowa. Seventy-eight percent of the county’s farm acres were treated with commercial fertilizers, and 23 percent were fertilized with animal manure. Nitrate readings for river samples were as high as 34.8 mg/l, far above the federal standard, the group said.

Chris Jones, a retired University of Iowa research scientist, said Iowa’s water quality problems are not going away.

“This vulnerability is going to increase, there’s no doubt about it,” Jones told the Des Moines Register. “Until the state’s leaders come to grips with that, we are going to continue to see these problems at a greater frequency.”

Jones said although the federal limit for nitrates is 10 mg/l, even as much as 3 mg/l may lead to certain cancers.

“If you live in Des Moines, you could go years without drinking water below 3 milligrams per liter,” he told the Register. “So, the fact that we are just meeting the standard at 10 and to do that we have to sacrifice lawn watering, well, that’s just a small part of the story.”

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Randy Evans is the executive director

of the Iowa Freedom of Information Council. He can be reached at DMREvans2810@gmail.com.