Ripple Effects: Here’s a refresher on the Nutrient Reduction Strategy

This explainer complements a two-part series, Ripple Effects, on the 10-year anniversary of the Nutrient Reduction Strategy. Read part one here, and part two here.

A raindrop splashes onto Iowa soil and rolls downhill, picking up nitrogen and phosphorous that plants use to grow tall and develop roots, fruits and flowers. It plops into a waterway and eventually spills into the Mississippi River. America’s second longest river carries it south and spits it into the Gulf of Mexico.

That’s the journey water droplets in the Mississippi River basin follow — and that’s the origin story of the Gulf of Mexico Hypoxic Zone, or dead zone. Nutrient pollution from 33 states fuels algae blooms that starve aquatic life of oxygen, causing up to $2.4 billion dollars in damage to fisheries and marine habitats every year.

That pollution creates problems where it originates, too, putting drinking waters supplies, ecosystems and recreation in danger.

In 2013, Iowa released its Nutrient Reduction Strategy to abide by Mississippi River/Gulf of Mexico Watershed Nutrient Task Force and U.S. Environmental Protection Agency directives. The strategy aims for a 45 percent reduction in total nitrogen and phosphorus pollution based on average nutrient loads from 1980 to 1996. Iowa’s state leadership chose not to adopt any timelines to reach that goal.

The two-pronged plan addresses nutrient pollution from point sources, like wastewater treatment plants and industrial facilities, and nonpoint sources, like runoff from croplands and urban areas.

Regulating discharges from point sources

Point sources contribute about a third of Iowa’s phosphorous pollution and about 10 percent of its nitrogen pollution.

To meet Task Force targets, Iowa point sources need to reduce 4 percent of their nitrogen contributions and 16 percent of their phosphorous contributions. To do this, the Nutrient Reduction Strategy directs the Iowa Department of Natural Resources to regulate nutrient discharges from point sources through permits.

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Nutrient removal is expensive, though, said Adam Schnieders, the Iowa DNR water quality resource coordinator. Establishing removal technologies at 130 facilities, plus operating and maintenance costs over 20 years, was estimated to cost $1.53 billion in present-day dollars — costs that would be passed to customers.

That’s why the Nutrient Reduction Strategy aims for technology-based or performance-based reductions from point sources — or, the reductions point source facilities can reasonably achieve with their available technology and financial resources.

The strategy focuses on 161 of the state’s biggest point source facilities: those designed to treat a million gallons of wastewater a day or more and could afford drastic upgrades. That includes 107 major municipal plants and 54 industrial facilities.

Those facilities had to complete two-year feasibility studies to determine how they could best achieve nitrogen and phosphorous removal. For the first time, they were issued permits that required them to monitor the nutrient levels in their discharges, which would inform their progress toward the strategy’s goals.

Based on the results of those studies, the Iowa DNR will devise a timeline for facilities to complete their necessary upgrades. Those commitments will be incorporated into their permits. Once the upgrades are complete, and following a year of nitrogen and phosphorous monitoring, new discharge limits will be added to facilities’ permits and become enforceable.

“Each one of these plants is so unique that the outcomes of these feasibility studies can vary significantly,” Schnieders said. “We've been implementing the process for 10 years, and we're starting to figure out where all the facilities fall.”

Voluntary conservation for ag

Nonpoint sources make up about 90 percent of the nitrogen and about two-thirds of the phosphorus entering Iowa waterways.

To meet Task Force targets, Iowa needs to reduce at least 41 percent of its nitrogen pollution and 29 percent of its phosphorus pollution from nonpoint sources. It has chosen to do so through voluntary measures for agriculture.

Iowa began its efforts with a comprehensive science assessment that mapped the state’s nutrient pollution. Scientists reviewed existing research to calculate a baseline for Iowa’s nitrogen and phosphorous loads — the “starting line” to improve from, said Jamie Benning, ISU’s assistant director for agriculture and natural resources extension.

They investigated sources of nutrient loss, studied best practices for mitigating it and identified gaps that future research should target.

The scientists behind the science assessment then created a “menu” of conservation practices available to help reduce the state’s nitrogen and phosphorous pollution from nonpoint sources.

They devised scenarios with different combinations of conservation practices that would successfully achieve the nutrient reduction goals, along with their estimated costs. They considered factors like lowering fertilizer application rates, increasing cover crop acreage, shifting tillage methods and building more wetlands.

These scenarios served as examples — not regulations.

“It wasn’t a prescription to say, ‘This is the way,’” Benning said. “It helped illustrate what was possible and what we needed to do — the magnitude of what needed to happen to reach the goals.”

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Brittney J. Miller is the Energy & Environment reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; brittney.miller@thegazette.com