Extreme levels of runoff stream from a farm field following a heavy rain May 29. (Iowa Environmental Council photo; click to view larger)
This has been yet another extraordinary spring for Iowa. After a record drought in 2012, spring 2013 is the wettest ever in 141 years of state records. According to National Weather Service estimates over the last sixty days, some portions of eastern Iowa have received between 200 and 300% of normal rainfall. As a result, river levels around the state are on the rise, especially in eastern Iowa, where fears of a repeat of the record 2008 floods continue to loom.
Estimated rainfall received in the 60 days ending June 2 show parts of Iowa (shown in dark blue) have received greater than twice normal precipitation. This heavy rainfall has placed Iowa’s natural resources under considerable stress. (Source: National Weather Service)
According to the DNR, heavy rains caused numerous municipal waste treatment systems to release raw sewage into waterways, and “a number” of open feedlots have also overflowed. In a release, the agency urged Iowans to avoid contact with floodwaters:
“People are urged to avoid ingesting or directly contacting flood waters, especially if they have cuts or abrasions that may be susceptible to infections from contact with bacteria. People with weakened immune systems should also avoid contact with flood water due to the potential contact with bacteria. Swimmers and anglers should thoroughly wash after coming in contact with water during flooding conditions.”
Heavy rainfall has placed Iowa’s natural resources under considerable strain. Removal of needed soil conservation efforts, like buffer strips, as well as the conversion of pasture and grassland to cropland, has accelerated the impact of recent rains. As was the case during last year’s drought, when Iowans encountered prolific algae blooms across the state, extreme weather conditions made Iowa’s lack of conservation preparedness especially clear.
Climate change appears likely to increase the number of major rain events occurring in our state over time. It is not possible for Iowans to control the amount of rainfall we receive; therefore, it is essential to use good conservation practices and other measures to limit the harmful effects of heavy rain. Many of these practices also maintain clean water for drinking, recreation and swimming in times of fair weather.
WASHING AWAY PRECIOUS TOPSOIL
With delayed planting on the state’s roughly 23 million acres of land used for row crops, a significant portion of the state’s land was at its most vulnerable to erosion last month. We have received numerous reports of extreme runoff from agricultural fields similar to what our own Nathaniel Baer witnessed traveling northeast of Des Moines on May 29:
In the last two months, parts of east central and northwest Iowa have suffered soil erosion at rates several times greater than so-called “tolerable” soil losses of 5 tons per acre in a whole year. As the map below from the Iowa Daily Erosion Project shows, some townships in Iowa suffered as much as 24 tons of erosion in the last two months alone–nearly 5 times the rate considered “tolerable” in a year.
In the last 60 days, portions of Iowa have suffered erosion at levels multiple times greater than what is considered “tolerable” for an entire year. (Source: Iowa Daily Erosion Project, Iowa State University)
These erosion impacts are not inevitable, even during heavy rains. According to the National Resource Conservation Service, many practices exist that can improve the ability of Iowa farmland to withstand major storms. For example, after 6-8 inches of rain fell on southeast Iowa April 17, Shawn Dettmann, an NRCS conservationist in Fairfield, made this observation:
“In fields where soil was disturbed through tillage, there are some rough areas with a lot of soil erosion,” said Dettmann. “In fields with high amounts of crop residue and little to no tillage, there was significantly less erosion, and in fields with these practices plus cover crops, there was little to no erosion.”
Extreme nitrate losses
Nitrogen and phosphorous pollution is always a serious problem in Iowa, even without heavy rains. According to the EPA’s 2008-2009 National Rivers and Streams Assessment, in the region including most of Iowa and Illinois, 72% of rivers and streams are rated “fair” or “poor” for total nitrogen.
This year, however, nitrogen pollution has been of particular concern. Earlier in May, levels in the Raccoon and Des Moines Rivers reached record levels, prompting the Des Moines Water Works to temporarily stop using water from the rivers to serve its customers for fear of violating the federal safe drinking water standard. Water Works data shows nitrogen and phosphorous levels in the Des Moines and Raccoon have been creeping upward for 30 years. The City of Cedar Rapids also expressed concern over drinking water when it detected high nitrate levels in the Cedar River.
The Iowa Department of Natural Resources estimated the commercial value of nitrates lost from these watersheds at nearly $93 million–and climbing–since April 1. (Source: Iowa DNR)
These losses also represent a major financial loss for Iowa’s farmers who apply nitrogen as a fertilizer. A recent analysis of initial real-time nitrogen monitoring data between April 1 and June 2 shows the commercial value of nitrate flowing past 9 monitoring sites has been nearly $93 million–so far. According to the Department of Natural Resources, 186 million pounds of nitrate from nitrogen fertilizer, manure, and other sources has been lost downstream during the last two months alone. The amount of nitrate being lost continues to climb.
Recently, state agencies released a final version of Iowa’s Nutrient Reduction Strategy which relies on extensive research by Iowa State University to suggest ways in which Iowa could significantly reduce nitrogen and phosphorous pollution, including from agricultural ground.
Unfortunately, the plan to implement that research relies on the same all-voluntary approach to conservation that has not prepared Iowa for the soil erosion and runoff challenges we face today. As a result, drinking water, the health of aquatic life, and Iowa’s agricultural soils remain at risk.
A CALL TO ACT
In order to resolve these problems, Iowa must successfully utilize additional conservation practices all across the landscape to hold heavy rains where they fall, prevent soil erosion, and keep polluted runoff from reaching rivers and lakes.
The Council’s executive director, Ralph Rosenberg, described Iowa’s challenge in a recent op-ed in the Cedar Rapids Gazette:
“It is time for us to embrace policies that move people and structures out of harm’s way, allowing wetlands and floodplains to slow and absorb excess water during spring floods. Wetland preservation and restoration, cover crops, grass waterways, buffer strips and other soil-conservation practices help the land act like a sponge, recharge groundwaters, and slow soil and nutrient loss from farmlands and urban areas.”
The Iowa Environmental Council supports the conservation action necessary to meet this challenge, and many of our member and cooperator organizations work actively in the area as well. However, recent evidence suggests Iowa has a long way to go before we can endure heavy rains without major human and environmental consequences. We need your support to help Iowa build healthier natural systems and be better prepared for the storms (or droughts) that lie ahead.