Mississippi River water quality has worsened in the last five years, spurred by agricultural runoff from Midwest states including Iowa, according to a new report from the America’s Watershed Initiative.
The group gave the Mississippi River watershed a C-, up slightly from a D+ in 2015, when looking at four metrics: water quality and ecosystems, flood control and risk management; transportation; and water supply.
But when focusing just on water quality, the river into which waters from 31 states flow and that makes up Iowa’s eastern border got a D.
“It’s a real concern that while we’re working on this issue and it’s been a priority of our state, we’re not making any more progress,” said Larry Weber, a University of Iowa professor of civil and environmental engineering and chairman of the institute’s report card committee. “In fact, we’re going in the wrong direction.”
In Iowa, the amount of nitrogen flowing into the Mississippi River has doubled in the past 20 years, with the annual load being more than 1 billion pounds two of the last four years, according to the report, which uses data from the Iowa Department of Natural Resources’ ambient stream monitoring.
Although nitrogen is naturally occurring, this outsize load comes from commercial fertilizer and manure that washes from corn and soybean fields into streams and rivers, Weber said.
Nitrate and phosphorus in the Mississippi River contributes to the Gulf of Mexico “dead zone,” an area of low or no-oxygen water that can’t support marine life.
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Over the last five years, the dead zone averaged 5,408 square miles, which is about three times larger than the Gulf of Mexico Hypoxia Task Force target of 1,950 square miles, the report said.
Although Iowa notes progress each year in the number of conservation practices — such as acres of cover crops, restored wetlands and installed bioreactors — those water quality measures aren’t keeping up with harmful practices, such as overapplication of manure, Weber said.
“The effort is far, far too small and the effort is being completely overshadowed by the intensification of agriculture,” he said. “We continue to put more subsurface draining in, use more commercial fertilizer, more livestock manure. That is completely overshadowing the good conservation practices.”
A 2018 UI study showed landowners in two western Iowa watersheds were applying nitrogen fertilizer at more than double the recommended rate, causing higher nitrate levels in streams there.
Although Iowa’s Nutrient Reduction Strategy does not have any mandatory steps for farmers, Weber would like to see state regulations on the amounts of manure and commercial fertilizer than may be applied.
President-elect Joe Biden said last week he plans to put more federal money toward incentives for farmers who plant cover crops and put land into conservation — steps that would improve water quality and could sequester carbon. He also wants American agriculture to achieve net-zero emissions.
Biden’s nomination of former Iowa Gov. Tom Vilsack to lead the U.S. Department of Agriculture, which Vilsack also led during President Barack Obama’s tenure, is encouraging to Weber.
“One of the things Secretary-nominee Vilsack could be working on would be how he could bring a focus to water resources,” Weber said. He’d like to see the Mississippi River get the same attention as the Florida Everglades and the Great Lakes — and a direct line of annual funding.
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“Secretary Vilsack is well aware of some of the best practices we’ve used in our state,” Weber said, pointing to the process of making targeted improvements across an entire watershed and measuring impact. “Some of those practices we’ve tested here in Iowa could provide incredible value.”
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