The Clean Water Act (CWA) required the Environmental Protection Agency (EPA) (defendant) to issue a final decision in a rulemaking within a certain amount of time. The EPA changed its procedural regulations to allow the presiding officer in rulemaking proceedings to discuss the proceeding with other EPA staff before issuing a final decision. Under these new procedural regulations, the EPA opened a rulemaking and proposed regulations restricting the discharge of certain toxic substances into waterways. Upon the close of the record in the proceeding, the presiding officer had approximately two months within which to issue a final decision under the CWA. The record contained thousands of pages from a variety of technical sources. The presiding officer consulted with other EPA staff before issuing final regulations in the proceeding. Hercules Inc. (plaintiff) brought suit challenging the regulations on the ground that the presiding officer violated the Administrative Procedure Act’s (APA) prohibition on ex parte communications by consulting other EPA staff.