Regulating Dams Through TMDLs

Kevin J. Beaton

In September 2002, the U.S. Environmental Protection Agency, Region 10 (EPA), at the request of the affected states, issued a preliminary draft temperature TMDL for the lower Snake River and Columbia River. TMDLs or “total maximum daily loads” are plans required under § 303(d) [33 USC § 1313(d)] of the Clean Water Act to bring a polluted waterbody back into compliance with state water quality standards. The draft TMDL raises significant issues concerning how dams will be regulated under the Clean Water Act.

The draft TMDL is an ambitious effort by EPA to quantify point source and nonpoint source temperature impacts to approximately nine hundred miles of two rivers that flow through portions of Idaho, Oregon and Washington and ultimately into the Pacific Ocean. The critical finding in the draft TMDL is that dams on the rivers are causing water temperatures to exceed state water quality standards. The existence and operation of these federally operated dams are important to the economy in the Pacific Northwest for the generation of electricity, flood control, irrigation and navigation. The lower Snake and Columbia Rivers also are critical habitat for a number of threatened and endangered salmonid species protected under the Endangered Species Act.

A key feature of the lower Snake River and Columbia River TMDL is the prediction of “natural background” or “site potential” river temperatures. Oregon, Washington, Idaho and Tribal water quality standards stipulate that when natural background pollutants, including temperature, exceed numerical criteria specified in the standards, natural background becomes the standard. Because of the recognition that temperatures in the two rivers were historically warmer than state criteria, the TMDL predicts what natural temperatures would be in the rivers by use of a mathematical model. Through the magic of computer modeling, dams and other anthropogenic sources of pollutants are removed to predict what river temperatures would be under natural conditions. However, since there were not enough data to predict the natural background of the more than 900 tributaries to the two rivers, EPA coined the term “site potential” to describe the predicted natural background temperature in the lower Snake River and Columbia River absent any tributary impacts.

The principal finding in the TMDL is that many of the dams on the rivers alter the temperatures in the impoundments behind the dams above “site potential” in the late summer and early fall. Since the TMDL concluded dams were the significant cause of water temperatures exceeding site potential criteria, the dams were given a negligible “load allocation” to reduce temperature in the rivers. A “load allocation” in a TMDL is the amount of loading capacity of a waterbody that is attributed to nonpoint source pollution. 40 CFR § 130.2(g). Significant point discharges of temperatures were provided a “waste load allocation” at existing thermal discharges rates because EPA found that point sources individually and collectively were having little or no impact on the “site potential” temperatures in the river.

There is no discussion in the TMDL regarding how the dams can achieve the load allocations necessary to achieve site potential temperatures. This is not surprising since achieving “site potential” temperature conditions would require that the dams be operated as if they did not exist. Implementation of the TMDL is not discussed and is left to each state. The establishment of a “load allocation” to dams in a TMDL in the manner specified in EPA’s draft TMDL appears to be a creative new way to address dams under the Clean Water Act. Throughout most of the thirty year history of the Clean Water Act, EPA has successfully argued that dams were nonpoint sources and were not required to obtain a NPDES permit. See National Wildlife Federation v. Gorsuch, 693 F.2d, 156 (D.C. Cir. 1982) (dams are nonpoint sources subject to state control because they do not add pollutants and, therefore, are not required to obtain a NPDES permit); National Wildlife Federation v. Consumer Power Company, 862 F.2d 580 (6th Cir 1988) (hydroelectric facility not required to obtain NPDES permit because it did not add pollutants). The establishment of a “load allocation” for each dam in the draft TMDL appears to be a step towards regulating dams as if they were point sources.

If dams are to be allocated loadings in a TMDL like other nonpoint sources, the draft TMDL may provide states with important data to impose controls on dams. Recently, EPA’s authority to establish TMDLs for solely nonpoint sources was upheld in Prosolino v. Nastri, 291 F.3d 1123 (9th Cir. 2002). In Prosolino, supra, the court also recognized that states were responsible for implementing TMDLs for nonpoint sources. Whether or how each state will make the difficult decisions to implement the “load allocations” for dams specified in any final temperature TMDL remains to be seen. Recently, a district court found that the Corps’ current operation of four of the dams addressed in the TMDL was consistent with the Corps’ obligations under the Clean Water Act. See National Wildlife Fed’n v. U.S. Army Corps of Eng’rs, CV 99-442-FR (D. Or. 2003). Whether the final TMDL will redefine those obligations may be the subject of another lawsuit. When EPA finalizes the lower Snake River and Columbia River temperature TMDLs and states begin implementation of the load allocations, the process will likely set a precedent on the regulation of dams by EPA and states under the Clean Water Act.

A copy of the preliminary draft TMDL can be obtained at EPA’s Web site at http://yosemite.epa.gov/R10/water.nsf. A formal draft TMDL subject to public comment will likely be published in the next few months. EPA plans to issue a final TMDL sometime in 2003.