On March 11, 2010, the Center for Biological Diversity voluntarily dismissed a 2009 lawsuit against U.S. EPA, in exchange for EPA's agreement to solicit public comment and consider issuing guidance to state agencies on the listing of state waters as threatened or impaired under the Clean Water Act due to greenhouse gas emissions to the atmosphere. In Center for Biological Diversity v. U.S. EPA, No. 2:09-cv-00670-JCC (W.D. Wash.), CBD alleged that EPA violated the Administrative Procedures Act and Section 303(d) of the Clean Water Act when it allowed the State of Washington to leave its ocean waters off the state's list of impaired waters.

Section 303(d) of the Clean Water Act requires each state to submit to U.S. EPA a biannual list of waters of that state that do not meet water quality standards and, as a result, require calculation of "Total Maximum Daily Loads" of pollutants. The purpose of a TMDL is to establish the maximum level of a pollutant that can be discharged to the relevant water body while still attaining applicable water quality standards.

CBD alleged that Washington's ocean waters failed to meet water quality standards for pH due to "ocean acidification" caused by carbon dioxide emissions to the atmosphere. According to CBD's Complaint, as the concentration of carbon dioxide in the atmosphere increases due to fossil fuel burning and deforestation, the amount of carbon dioxide absorbed by seawater increases, leading to a lowering of the water's pH, which in turn impairs the ability of marine animals to build and maintain shells and skeletons.

To settle the case, EPA issued a request for public comment on March 22, 2010. CBD's Complaint does not seek to explain—and, interestingly, EPA's public notice does not expressly seek comment on—how a locally focused measure like the Clean Water Act's TMDL process might effectively redress the effects of a globally caused phenomenon like the atmospheric concentration of carbon dioxide. The request will remain open until May 21, 2010.