TMDL: Coming Your Way?

August 25, 2015 04:01 PM
TMDL: Coming Your Way?

For its first 40 years, the federal Clean Water Act (CWA) left agriculture largely untouched. Until recently, the Environmental Protection Agency (EPA) primarily focused on “point sources” of water pollution, such as sewage treatment plants or waste flows from industrial operations. With the exception of CAFOs (large feedlots and confinements), most water pollution originating from agricultural operations is considered “nonpoint source” pollution.

The CWA does not place a significant emphasis on controlling nonpoint source pollution. However, after making progress on controlling point sources of pollution, many of our major waterways remain less than pristine. EPA has now turned its attention to regulating nonpoint sources, and agriculture is one of its primary targets.

EPA’s preferred method of nonpoint source pollution is called the Total Maximum Daily Load, often referred to as the TMDL. It’s essentially a document that identifies the maximum amount of point source and nonpoint source pollution a waterway can absorb while retaining sufficient quality to support aquatic life. Under the CWA, states are required to develop TMDLs for waterways that cannot meet water quality standards solely through the control of point sources. These are executed by states setting more stringent limitations on point sources and encouraging reductions of nonpoint source pollution through Best Management Practices (BMPs).

The primary targets for reduction of nonpoint source pollution are agriculture and construction. Both are sources of sediment runoff, and agriculture (along with golf courses and residential lawns) is a significant source of nutrient runoff. These nonpoint sources are generally controlled through BMPs, such as installing riparian buffers or planting cover crops. BMP adoption is often encouraged through cost-share programs; however, states have the authority to mandate BMPs.

Frustrated with the slow pace of state TMDL efforts, EPA is starting to take matters into its own hands. The CWA also provides EPA with the authority to establish TMDLs for waterways. However, the language of the CWA is vague in terms of whether EPA can require states to implement a TMDL through nonpoint source restrictions.

EPA’s first target for a major TMDL is the Chesapeake Bay. Under the Bay TMDL, EPA initially divided the estuary into 92 segments, separating point sources and nonpoint sources for sediments, nitrogen and phosphorus. Once the TMDL was established, states were required to develop individual Watershed Implementation Plans (WIPs) to determine how they will actually achieve their water quality goals, through point source reductions and BMP implementation. The states are required to submit periodic updates on the progress made under their WIPs.

American Farm Bureau Federation and other agricultural groups recently challenged EPA’s authority to require states to enforce the federal Bay TMDL. In July, the Third Circuit Court of Appeals rejected Farm Bureau’s challenge, holding the CWA could be interpreted to allow EPA to implement a TMDL for multijurisdictional waterways, such as the Chesapeake Bay. At this point, Farm Bureau has not indicated whether it will further appeal this decision.

Assuming the Bay TMDL decision stands, the legal path is clear for EPA to apply the lessons learned during the Bay TMDL to other major watersheds. In terms of agriculture, the most significant watershed is the Mississippi River. In the future, farmers and ranchers operating in this watershed will likely face increased restrictions on fertilizer/manure applications and will adopt, via carrot or stick, more conservation-minded BMPs.

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