WASHINGTON - A new Environmental Working Group report examines water pollution caused by farm runoff and details how treating the problem after the fact is increasingly expensive, difficult and, if current trends continue, ultimately unsustainable.
Water that runs off poorly managed fields that have been treated with chemical fertilizers and manure is loaded with nitrogen and phosphorus. These two potent pollutants set off a cascade of harmful consequences, threatening the drinking water used by millions of Americans.
Nitrate, the most common form of nitrogen in surface and groundwater, is directly toxic to human health. Infants who drink water with high nitrate levels can develop an acute, life-threatening blood disorder called blue baby syndrome. High nitrate levels in water can also affect thyroid function in adults and increase the risk of thyroid cancer.
Phosphorus stimulates explosive blooms of aquatic algae, including the especially dangerous cyanobacteria (blue-green algae) that produce toxins that can be deadly to pets, livestock, wildlife – and people. Toxins produced by cyanobacteria can harm the nervous system, cause stomach and intestinal illness and kidney disease, trigger allergic responses and damage the liver.
“Access to clean and healthy drinking water is a critical issue for Americans and the rest of the planet. The only solution to preserve clean water is to tackle the problem of polluted agricultural runoff at the source,” said EWG senior scientist Olga Naidenko PhD, lead author of the report.
“A strong conservation title in the new farm bill is our best opportunity to help farmers protect drinking water,” said co-author Craig Cox, EWG senior vice president of agriculture and natural resources. “We can’t afford anymore cuts to conservation programs, and Congress must bring crop and revenue insurance programs back under the conservation compact between farmers and taxpayers.”
The so-called “conservation compliance” provisions Congress wrote into the 1985 farm bill established the compact. Farmers agreed to undertake common sense measures to limit pollution, cut soil erosion and protect wetlands in return for generous farm subsidies. The heavily subsidized crop and revenue insurance program has become the single most expensive farm subsidy – and has no conservation requirements attached.
Every year, farm operators apply more than 12 million tons of nitrogen fertilizer and 8 million tons of phosphorus fertilizer to agricultural land in the U.S. Unless carefully managed, nitrates and phosphates are carried off their fields by runoff water or percolates into drainage systems, eventually ending up in streams, rivers, lakes and underground aquifers.
Many American farmers engage in responsible land and water stewardship. But the list of American waters imperiled by agricultural pollution grows daily and now includes the Chesapeake Bay, the Great Lakes and the Gulf of Mexico. U.S. Department of Agriculture researchers estimate that on two-thirds of the nation’s agricultural land, fertilizer use does not conform to science-based best management practices. Growers spread too much, spread it at the wrong times and use methods that are prone to losing nutrients into runoff. In addition, installation of “tile drainage,” which is common across the Midwest, promotes the movement of nutrients into streams.
National studies and regional assessments of waterways in the Mississippi River Basin consistently point to chemical fertilizers and manure spreading on fields as the main sources of nutrient pollution. USDA economists estimate that the national costs of removing nitrate alone from drinking water total more than $4.8 billion a year. Water treatment to address nutrient-fueled algal and cyanobacterial blooms and cyanotoxins can carry a total capital cost can range between $12 million and $56 million for a town of 100,000 people.
Most farm operations are exempt from the pollution control requirements of the federal Clean Water Act, and few states have little authority to compel farmers to reduce water contamination.