Twitter UpdatesEROSION’S LONG, DESTRUCTIVE TRAIN – Page 2
Agricultural runoff is a major contributor to the poor scores Iowa’s streams and rivers get in a water quality index maintained by the Iowa Department of Natural Resources. In 10 years of monitoring at 90 sites around the state, no site earned an excellent water quality rating, and only two were ranked good. Seventeen were rated fair, 67 poor and 4 very poor.21
Nationwide, the impact is staggering. Among the documented problems in which agricultural runoff plays a critical role:
- 100 percent increase in drinking water violations because of nitrate contamination between 1998 and 200822
- nitrate contamination in 72 percent of 2,100 private wells sampled by the U.S. Geological Survey between 1991 and 200423
- 104,321 miles of rivers and streams rated as impaired24
- 1,579,540 acres of impaired lakes, reservoirs and ponds 25
- 2,885 square miles of impaired bays and estuaries26
- 383,822 acres of impaired wetlands.27
The damage continues downstream to the Gulf of Mexico, contributing to the largest dead zone in U.S. coastal waters and the second largest in the world.28 The Mississippi River/Gulf of Mexico Watershed Nutrient Task Force set a goal of reducing the size of the dead zone to less than 1,900 square miles, but the dead zone has been larger than that every year since 1990, except for 2000. From 2003 to 2007, the five-year was 5,600 square miles, more than twice the goal.29
In 2010 the dead zone swelled to 7,722 square miles, about the size of New Jersey.30
Iowa is getting more precipitation, more frequent rains and heavier rainfalls then when I was a farm boy in the 1950s and 1960s. Even then, I knew if we tilled through a swale that should have been kept in sod we would watch that soil wash away the rest of the year. It was very predictable then that concentrated runoff would carry the soil downstream, and it is even more predictable with the weather we have now. Some of the worst soil erosion now comes from heavy rains in late winter after freeze-thaw cycles have loosened the soil.
Each spring too many farmers still use their tillage equipment to fill in ephemeral gullies so they can plant through them another year. I wonder if the landowners are not watching, don’t understand or just don’t care. Most of Iowa’s farmland is rented; about half was inherited or purchased for investment; and about one-third of landlords live out of state or far away from the farm.
Iowa’s weather is changing and so is farmland ownership. Society can no longer assume that landowners see or comprehend what is happening with their precious land and with our priceless waters. Government needs to step up enforcement of soil conservation laws, especially with absentee landlords who are not around to see and be responsible for what is happening.
Duane Sand
Iowa Natural Heritage Foundation
Des Moines, Iowa
