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Ontario Grain Farmer Magazine is the flagship publication of Grain Farmers of Ontario and a source of information for our province’s grain farmers. 

US Clean Water Act


THE UNITED STATES’ Clean Water Act (CWA) involves a bewildering array of acronyms for programs that can affect US farm practices in general and, because of its high nitrogen needs, corn production specifically. 


Pollutants regulated under the CWA include excess levels of sediment from soil erosion, crop nutrients such as nitrates, pesticides, and pathogens from livestock production. CWA enforcement initially focused on point- source pollution that could be readily monitored – for example, pollution flowing from city sewage systems, factories, processing plants, construction sites, or concentrated animal feeding operations (CAFOs) that release pollutants through pipes or ditches. These operations must have a CWA permit that specifies exactly how much of a pollutant they can release into their watershed and CAFOs must have a manure management plan (MMP). Farmers who apply manure from out-of-state to their fields may also need an MMP.

Even with permits in place, however, many waterways do not meet CWA standards. That failure triggers a Total Maximum Daily Load (TMDL) which sets a limit on the total amount of a pollutant that can be released into a given body of water during a specific period. The TMDL is then divided among permit holders and contributors who are exempt from permitting, such as leaching out of fields, pasturing operations, or rural septic systems. 

By 2007, more than 60,000 TMDLs had been identified by the individual states, which are responsible for calculating allocations. States may also choose to work with the Environmental Protection Agency (EPA) to develop an implementation plan for a TMDL.
For a corn grower farming in a watershed with high pollution levels, this could mean pressure to adopt pollution controls such as Best Management Practices (BMPs), creating new management demands. A TMDL could also affect crop inputs. For example, the TMDL for the Chesapeake Bay targets a 25% drop in nitrogen levels, a 24% drop in phosphorus, and a 20% drop in sediment. That affects more than 87,000 farming operations from as far away as western New York and southwestern Virginia.
The most far-reaching TMDL developed to date, it could ultimately make certain nutrient management practices mandatory, establish permitting requirements for nutrient applications, restrict the times when nutrients could be applied, or even ban some practices. 

Buff Showalter, a Virginia corn and livestock producer, outlines the problems he would face: “We’re living on the edge of having to back off yields,” he says of his farm, which drains down the Shenandoah and Potomac rivers into the bay some 250 miles away. “If we’re limited on the nutrients we can apply, and then we get a ten-inch rain during the critical crop take-up period, our yields will suffer.”

He is also concerned that the TMDL could restrict his use of poultry litter because of its high phosphorus content. “It hurts to buy more expensive commercial fertilizer when you’ve got product sitting in the shed, especially since there’s a question whether phosphorus moves much if you’re doing no-till,” he says.

The same issues arise for even more farmers in the Corn Belt, where excess nutrients are an issue from the headwaters of major rivers down to the Gulf of Mexico. In the Upper Mississippi River Basin alone, 33 TMDLs target excess nutrient reductions.

Like Showalter, Midwestern farmers talk about wanting to do the right thing for the environment, but they are concerned about how TMDLs will be enforced, who will enforce them, and what will be required – a key issue since questions have been raised about the accuracy of the EPA’s computer model to determine pollution sources.
Last fall, a US district court ruling on TMDLs opened the door for the EPA to make pollution control practices mandatory. The decision has been challenged in court by the National Corn Growers Association, which warns that the case could set a precedent for other watersheds beyond the Chesapeake. At the same time, more options to help farmers reduce nutrient losses are being touted — ranging from sensor-controlled variable rate nutrient application to modified field drainage systems to reduce runoff and the adoption of cover crops to sequester nitrogen. •


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