Clarifying Regulatory Relief: Illinois Pollution Control Board Upholds Thermal Alternative Effluent Limit for Waukegan Generating Station

The Waukegan Generating Station, like many power plants, uses an “open-cycle” water intake to cool its equipment, and this results in heated effluent being returned to the water body. Heat is considered a “pollutant” under the Clean Water Act, but a thermal discharger can seek regulatory relief by showing that its discharge does not significantly affect local aquatic life. The Waukegan Station applied for and obtained this “alternative effluent limit” relief in 1978, and the Illinois EPA continued to renew the thermal alternate effluent limit in each of the Station’s subsequently issued NPDES permits, including the renewed 2015 permit. Subsequent to the completion of the public notice and comment periods for the 2015 permit, the Board adopted new Illinois Subpart K regulations (35 Ill.Adm.Code Subpart K) which apply to the original issuance and renewal of thermal alternative effluent limitations. The Board found that the new Subpart K regulations applied because they were effective at the time of the permit’s issuance. The Board’s Opinion clarifies the applicable requirements and criteria for renewal of thermal alternative effluent limits and found that the petitioners had failed to prove that the Agency’s decision to renew violated the Subpart K regulations.

The Clean Water Act also has requirements for cooling water intake structures, because of the potential for aquatic life to be impinged (when fish and other aquatic life are trapped against cooling water intake screens) or entrained (when aquatic organisms, eggs and larvae are drawn into a cooling system). Although the Waukegan Generating Station had repeatedly been found to use the “Best Technology Available” (BTA) since 1978, the U.S. EPA changed the rules for cooling water intake structures pursuant to Section 316(b) of the Clean Water Act shortly before thethe 2015 NPDES Permit was renewed. On appeal, the petitioners unsuccessfully challenged the Agency’s decision that the Station’s cooling water intake structure met the “interim BTA” standard set forth in the new Section 316(b) rule.

The Board’s opinion can be read here.