Regulating water intake structures
Section 316(b) of the federal Clean Water Act requires, and Section 283.31(6), Wis. Stats., allows the department to require that the location, design, construction and capacity of cooling water intake structures reflect the best technology available (BTA) for minimizing adverse environmental impact. The department’s authority to regulate intake structures is tied to the issuance of Wisconsin Pollutant Discharge Elimination System (WPDES) permits and is found in s. 283.31(6), Wis. Stats:
Any permit issued by the department under this chapter that by its terms limits the discharge of one or more pollutants into the waters of the state may require that the location, design, construction and capacity of water intake structures reflect the best technology available for minimizing adverse environmental impact.
In 2014, the EPA completed a new final rule to establish requirements under section 316(b) for all existing facilities that withdraw greater than 2 MGD and use at least 25% of that water exclusively for cooling purposes (79 FR 48300, Aug. 15, 2014). This rule establishes national requirements for the location, design, construction and capacity of cooling water intake structures by setting requirements that reflect BTA for minimizing adverse environmental impact and must be implemented through NPDES permits. The 2014 rule became effective on Oct. 14, 2014.
Implementing 316(b) in Wisconsin
Since the federal regulations for 316(b) were promulgated in 2014, the DNR is required to determine whether cooling water intake structures meet federal standards for best technology available at each reissuance of a WPDES permit. DNR promulgated ch. NR 111, Wis. Adm. Code, in 2020 in order to implement the federal regulations in Wisconsin.
Federal regulations and ch. NR 111, Wis. Adm. Code, establish requirements under section 316(b) for all existing facilities that withdraw > 2 MGD design intake flow from waters of the U.S. and that use > 25% of their intake water exclusively for cooling purposes. For existing facilities that fall below either of these thresholds, BTA determinations must be made using best professional judgment, according to 40 CFR 125.90(b) and s. NR 111.02 (7), Wis. Adm. Code.
The guidance provided at the link below is intended to help staff use their best professional judgment to decide whether intake structures meet BTA requirements.