Increasingly, complaints are being lodged about runoff and discharged water from U.S. farms and other sources, such as industries and metropolitan areas, by downstream users of the water who raise concerns about its safety to drink, as well as the costs to treat contaminated water to make it drinkable.  

Last week’s Farm and Ranch Life column provided information about the availability of water worldwide for agriculture and other uses.  Underground aquifers have almost been used up in some countries and are dwindling slower–but declining nevertheless–in key agricultural-producing regions of the U.S., chiefly the seven western-most states and the Ogalalla Aquifer which underlies parts of seven High Plains states. 

This week’s article looks at agricultural water runoff.  Are complaints of downstream users legitimate that their water is contaminated by fertilizers, pesticides, manure and other toxic substances?  How much of the claimed pollutants are due to agriculture?

The Des Moines Water Works lawsuit and WOTUS.  These two important matters have come to symbolize many of the issues alleged about agricultural runoff and discharged water. 

The Des Moines Water Works lawsuit is a test-case against three highly agricultural counties in Iowa which claims the governments of these counties should be held accountable for allowing high amounts of nitrates to enter the Raccoon River, a major water source for the downstream city of Des Moines.  The Des Moines Waterworks is a separate entity from the city of Des Moines. 

WOTUS (Waters of the United States) is a federal provision that supersedes state regulatory agencies if they do not fulfill expected requirements to protect water supplies.  Drawing on the Clean Water Act approved by Congress forty years ago, WOTUS seeks to regulate all water runoff and discharges it deems necessary.   

There is much opposition from individuals, businesses and organizations that insist state and local control should take priority.  Critics say WOTUS over-reaches and that farmers can’t be blamed for excessive rains or runoff of melting snow from frozen farm fields where manure or fertilizers have been applied.

Are complaints of water pollution by agricultural activities legitimate?  The Des Moines Water Works suit cites data collected by the Iowa Nutrient Research Center–established by the Iowa Legislature in 2013–that indicates 92 percent of nitrates and 80 percent of phosphorus entering Iowa streams originates from farms. 

The legal issues of responsibility may take several years to sort out.  Among the matters to be determined is whether county governments or other entities, such as state or federal governments or farmers themselves, should be responsible for failing to control contaminated water from entering surface waterways and drainage tile lines on farmland. 

A related question is: Why are farmers installing drainage tile lines to collect water on hillside ditches that seldom transport water except during exceptional precipitation events?  Dry soil during drought could limit the water available when most needed. 

There are broader issues than nutrient discharge.  A 2013 Livescience report indicated that 59 percent of monitored U.S. waterways were contaminated to the point that these waterways were not safe for recreation, drinking or for consumption of their fish.  Two decades earlier 36 percent of the monitored waterways were deemed contaminated.

The causes of the pollution are varied.  Besides high levels of nitrates and phosphorus, other pollutants have been identified by a growing number of scientific studies. 

Pollutants include toxins and endocrine disrupters from pesticides, human and animal sewage and other sources, as well as antibiotics, cancer-enhancing chemicals, heavy metals and many more hazardous substances.  Some are point-source pollutants, such as discharges from mines or industrial sites, and others are nonpoint sources such as runoff from farm fields. 

How much of the contaminated water can be attributed to agriculture?  There are no fully certain answers.  That is partly why the EPA is proposing WOTUS. 

The EPA lays out its aims in the website: www.epa.gov/cleanwaterrule.  It seeks a balance between the need for potable water and economic prosperity.

The concerns that some farmers have about state and federal environmental regulations are somewhat understandable when they assert governments intrude on their rights and efforts to produce necessities for life—food, fibers and increasingly, renewable fuels. 

In the end, however, everybody needs water that is safe to drink and use for other purposes.  Farmers could be doing more to protect runoff caused by weather events and discharges from agricultural enterprises.

During recent years of prosperous farming, much farmland was removed from Conservation Reserve Programs that promoted and paid for filter strips and grassed waterways.  Many farmland owners installed questionably necessary drainages that enhance the filtration of applied fertilizer, manure, naturally-occurring nutrients and farm chemicals of all types into waterways. 

It’s time for agricultural producers to take an honest look at what can be done to improve water conservation and quality.


Dr. Rosmann lives on a farm near Harlan, Iowa and is Adjunct Professor at the University of Iowa in the Department of Occupational and Environmental Health.  He can be contacted at: www.agbehavioralhealth.com.