On May 19, 2014, EPA released its long awaited final regulations under Section 316(b) of the Clean Water Act to establish requirements for cooling water intake structures (CWISs) at existing facilities. (An existing facility is any facility that commenced construction on or before Jan. 17, 2002.) The regulation establishes control requirements for CWIS to protect aquatic life from impingement on intake screens and entrainment into cooling systems at existing electric generating utilities and manufacturing facilities. The regulation also amends the impingement and entrainment protection standards for CWIS at new facilities. The regulation will become effective 60 days after it is published in the Federal Register. Section 316(b) requires application of the best technology available (BTA) for minimizing adverse environmental impact due to operation of CWISs.

With respect to CWISs at existing facilities, the regulation establishes standards and requirements for facilities that are designed to withdraw more than 2 MGD of water and use at least 25 percent of the water exclusively for cooling purposes. The existing facility standards will regulate 99.8 percent of the total cooling water withdrawals at such industries and apply to an estimated 1,065 existing facilities. Approximately half of the regulated facilities are manufacturers and the other half are electric generating utilities.

After the rule’s effective date, existing facilities within the scope of the rule are subject to standards for impingement mortality under one of seven primary alternatives. These include: use of closed cycle recirculating systems (e.g., cooling towers); limitation of the design or actual through-screen intake flow velocity to 0.5 feet per second; use of an existing off-shore velocity cap; use of modified traveling screens with a fish-friendly fish return; use of a system of technologies, management practices, and operational measures identified through an impingement technology performance optimization study; or demonstrated compliance with the impingement mortality standard (i.e., no more than 20 percent mortality for all non-fragile species collected or retained in the specified sieve).

With respect to entrainment standards for existing facilities, EPA found no single technology that would represent BTA on a uniform national basis. EPA also did not identify a basis for subcategorizing existing units at which flow reduction technologies are feasible. Accordingly, BTA standards for entrainment for each intake are to be determined by the permitting authority on a site-specific basis.

New units at existing facilities must reduce design intake flow for the new unit to a level commensurate with that which can be achieved by a closed-cycle recirculating system. Alternatively, new units must reduce the level of adverse environmental impact from any cooling water intake structure to a comparable level to that achieved by such a closed-cycle recirculating system.

Additional measures may also be required at existing and new units, including monitoring requirements and reporting requirements, to minimize incidental take of federally-listed endangered species and designated critical habitat.

The standards for CWISs at existing facilities are to be implemented through NPDES Permits. For facilities with existing NPDES Permits that expire 45 months or more after the effective date of the final rule, the next NPDES Permit renewal application must contain the requisite information for the permitting authority to determine impingement and entrainment requirements for the facility. For facilities with NPDES Permits that expire within 45 months of the effective date of the final rule, alternate schedules for submission of the required information are available. NPDES Permits that have expired and are reissued for existing facilities within 45 months of the effective date of the final rule are not required to include final impingement and entrainment standards in the reissued NPDES Permit. Those permits may include requirements to submit the requisite information in the next permit application. However, the regulation provides that “in addition, the [permit authority] must establish interim BTA requirements in the permit based on the [permit authority’s] best professional judgment on a site-specific basis in accordance with ... 40 CFR 401.14.”

The NPDES Permit that establishes final compliance standards is also to require compliance with the impingement and entrainment requirements as soon as practicable. Interim compliance milestones may be included in the permit. For new units (those that have not commenced construction prior to the effective date of the rule), compliance with impingement and entrainment standards must be met upon startup of the new unit.

Finally, the regulation also notes that existing facilities that are below the 2 MGD intake flow threshold are subject to permit conditions implementing BTA requirements as developed on a case-by-case basis through best professional judgment. See 40 CFR 125.90(b). Accordingly, industrial facilities with small cooling water needs may also be subject to impingement and entrainment control standards set through BPJ by state permitting authorities.