Environmental groups and paper and pulp mills brought suit challenging, for different reasons, an action of the Environmental Protection Agency (EPA) under the Clean Water Act (CWA) in setting a Total Maximum Daily Load (TMDL) limiting the amount of dioxin that could be released into the ColumbiaRiver Basin. The district court granted summary judgment in favor of EPA. The environmentalist group Dioxin/Organochlorine Center (DOC) and Longview Fibre Co. appealed, seeking to overturn the summary judgment.

DOC argued that EPA standards were not stringent enough in that they failed to implement the preexisting state water quality standards. It contended that the EPA standards were flawed because they 1) inadequately protected aquatic life and wildlife, 2) inadequately protected specific human subpopulations, and 3) failed to consider the cumulative effect of dioxin-related pollutants in the water system.

The court held that, based on EPA documents and the testimony of one of the principal developers of the TMDL, EPA's decision to set the TMDL adequately considered the protection of aquatic life and wildlife and human subpopulations. On the issue of considering the cumulative effect of other pollutants in the river, the court held that the CWA did not require EPA to issue TMDLs for all pollutants at one time. Thus, the court concluded that EPA's decision was within the reasonable limits of its discretionary authority. Since DOC could not show EPA's decision to be arbitrary and capricious, the decision of the district court was upheld.

The pulp mills argued that EPA should not have set any TMDLs at all. They based this conclusion upon their interpretation of 33 U.S.C. § 1313(d)(1)(A), under which they argued EPA was prohibited from developing TMDLs prior to the proven failure of technology-based limitations. They pointed to the legislative history of the CWA in support of their claim. EPA argued that the section required TMDLs where existing pollution controls did not lead to attainment of water quality standards.

The court held that EPA's interpretation was reasonable because under the CWA, toxic pollutants such as dioxin were not subject to best practicable technology limitations, but rather to best available technology limitations (BAT). Moreover, the court specifically held that section 303(d)[1] allows EPA to establish TMDLs for waters contaminated with toxic pollutants without prior development of BAT limitations. It held EPA's interpretation was not contrary to congressional intent, since it fit within the legislative history of the CWA, which placed a priority on the rapid reduction of known toxic pollutants. Since EPA's interpretation and application of the CWA was found to be reasonable, there was no basis for overturning the summary judgment.