The question of how to regulate temperature in water bodies is one that states in the Northwest have struggled with for years. The U.S. Environmental Protection Agency (EPA) addressed that question on May 18, 2020, when it released a draft Total Maximum Daily Load (TMDL) to achieve water quality standards for temperature in certain reaches of the Columbia and Lower Snake Rivers in Oregon and Washington. This new TMDL comes a few months after a decision from the U.S. Court of Appeals for the Ninth Circuit, Columbia Riverkeeper v. Wheeler, requiring the agency to take the lead after Oregon and Washington failed to submit their own TMDL. Comments on the draft TMDL are due by the end of July 21, 2020.

A TMDL represents a total cap on pollutants that may be discharged to covered segments, and that cap is divided among wasteload allocations for point sources (which hold NPDES permits), load allocations from non-point sources, and a margin of safety. These allocations are not directly enforceable against dischargers. But they can be implemented through enforceable limits or practices in permits or water quality certifications issued by state agencies. Dams, for instance, might see the final TMDL impact the Clean Water Act Section 401 certifications required for relicensing before the Federal Energy Regulatory Commission or in NPDES permits.

Indeed, dams are a particular focus of the draft TMDL, which examines both their cumulative and individual impacts on temperature. An apparent impact from a dam on river temperature might not necessarily require reductions in that impact, depending on the local water quality standards and the dam’s relative contribution. The analyses included in the TMDL demonstrate that, on a reach-by-reach basis, the dams in these water ways are not the cause of the elevated temperatures.

The draft TMDL also recognizes that external factors, including climate change and the fact that the temperature of the water entering the rivers from Canada or Idaho, are the primary contributors to elevated temperatures, causing the state water quality criteria to be exceeded even before the water reaches the dams. These causes are beyond the scope of the TMDL, in fact, and might ultimately require the covered states to rethink and revise their current standards for temperature.

The TMDL highlights the need for flexibility in implementation. Washington and Oregon will now have to determine whether they will employ that flexibility as they implement the TMDL. Once the TMDL is finalized, the states must develop implementation plans, providing facility-specific allocations and determining how those allocations will be enforced. Recent Section 401 certifications issued by the Washington Department of Ecology on May 7, 2020, for federal hydropower projects in the Columbia River suggest that the states will impose temperature requirements on individual facilities. The Section 401 certification provides that permittees “must implement temperature control strategies and meet the load allocations in the Columbia and Lower Snake Rivers Temperature Total Maximum Daily Load once issued.”