Information requests under Clean Water Act (CWA) Section 308 are one of several important tools the EPA uses to obtain necessary and appropriate information to study discharges of pollutants and make regulatory decisions. EPA uses Section 308 letters as part of its effluent limitations guidelines development process and when implementing programs such as the National Pollutant Discharge Elimination System or Total Maximum Daily Loads. EPA's Office of Water issued a memorandum in 2018 clarifying its processes for collecting information from the regulated community under Section 308.

• Policy: Use of Clean Water Act Section 308 Letters (PDF)(6 pp, 2 MB, November 2018)