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Corn+Soybean Digest

TMDL Spells Caution

Help head off water quality problems If you haven't heard of TMDL, you will. It stands for total maximum daily load, and it pertains to the water quality of streams and lakes.

TMDL is the amount of a given pollutant, such as sediments, excess nutrients or harmful microorganisms, that can be allowed to enter a water body and still meet water quality standards.

A fact sheet issued jointly by the American Soybean Association (ASA) and the National Corn Growers Association (NCGA) explains that a TMDL is also a blueprint for identifying and cleaning up an impaired stream or lake.

Individual states are responsible for establishing and implementing TMDLs. Communities within watershed areas will determine how to control pollutants if those pollutants impair water quality. But EPA (Environmental Protection Agency) can step in if that agency deems it necessary. This, in fact, has happened.

TMDLs will continue to be established over the next 15 years.

"Under current law, each state must submit water quality reports to EPA every two years," explains Jim Porterfield, technical specialist on land, water and forestry resources for the American Farm Bureau Federation. "EPA summarizes those reports for its report to Congress. Some regional EPA offices have encouraged states to submit as many water bodies as possible as impaired or threatened since that makes more funding available.

"The upshot," says Porterfield, "is that farmers need to get busy and see whether the reports from their states are backed by credible sources and credible data."

Porterfield points out that the people reporting impaired bodies of water don't actually need to test those waters. They can do it by "evaluation." That means they can merely look at a map and subjectively label a body of water as impaired, even without a water sample.

"We have heard numerous horror stories," Porterfield says.

In 1996, over 50% of stream miles reported as impaired by agriculture in 14 states were based on "evaluated" information. In 1998, the latest year for which data are available, 13 states were in that category.

"Eventually, we could see regulations that require farmers to get permits for applying fertilizer, chemicals and manure to their fields," says Porterfield.

"There is still a small window of opportunity for farmers to voluntarily clean up their acts and convince Congress and the public that we have enough regulation. But that window is closing fast," he adds.

He suggests that farmers collect their own water quality data from streams receiving drainage from their farms to protect themselves. This includes sampling where streams enter and leave property and at strategic locations where concentrated surface runoff occurs or tile drains outlet.

ASA and NCGA urge farmers to participate in the planning and implementation of local TMDL projects. They advise growers to contact their local conservation districts or Natural Resources Conservation Service offices to learn the critical water quality issues and whether those issues pertain to agriculture. (Municipalities, golf courses, etc., are also affected by TMDLs.)

Farmers may want to check with their state grower associations for guidance.

In Iowa, the state's corn and soybean grower associations are organizing networks of farmers in watersheds across the state to promote best management practices. That could head off problems before they begin.

To learn more about the TMDL program and about individual state water control agencies, check the EPA Web site (

To see a copy of "What Farmers Need To Know About Clean Water and TMDLs," go to NCGA's Web site (

Bottom line to growers: "Get a seat at the table," advises Krysta Harden, ASA representative in Washington. "Farm groups may question EPA's jurisdiction over non-point sources of pollution, such as agriculture, but agriculture can't ignore the regulatory potential."

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