The US Environmental Protection Agency’s long awaited and much anticipated Section 316(b) rule on requirements for cooling water intake structures at existing power plants and other facilities has been finalised, after several postponements, over three years from when the new proposed rule was issued for public comment, in March 2011. The issuing of a final rule, on 19 May, marks the culmination of a tangled law making process, which, remarkably enough, started in 1972 with enactment of the US Clean Water Act (CWA).

The new rule aims to protect fish and other aquatic life forms drawn each year into cooling water systems at large power plants and factories. It is required by the Clean Water Act to address site-specific challenges, and, says the EPA, establishes a common sense framework, putting a premium on public input and flexibility for facilities to comply.

"The rule covers roughly 1065 existing facilities, of which 544 are power plants"

An estimated 2.1 billion fish, crabs, and shrimp are killed annually by being pinned against cooling water intake structures (impingement) or being drawn into US cooling water systems and affected by heat, chemicals, or physical stress (entrainment).

"EPA is making it clear that if you have cooling water intakes you have to look at the impact on aquatic life in local waterways and take steps to minimise that impact," said Nancy Stoner, acting Assistant Administrator for Water at EPA.

The final rule establishes requirements under the CWA for all existing power generating facilities and existing manufacturing and industrial facilities that withdraw more than 2 million gallons per day of water from waters of the US and use at least 25% of the water they withdraw exclusively for cooling purposes. The rule covers roughly 1065 existing facilities, of which 544 are power plants. The technologies required under the rule are "well-understood, have been in use for several decades, and are in use at over 40 percent of facilities", says the EPA.

There are three components to the final regulation.

  • Existing facilities that withdraw at least 25% of their water from an adjacent waterbody exclusively for cooling purposes and have a design intake flow of greater than 2 million gallons per day are required to reduce fish impingement. To ensure flexibility, the owner or operator of the facility will be able to choose one of seven options for meeting best technology available requirements for reducing impingement.
  • Facilities that withdraw very large amounts of water – at least 125 million gallons per day – are required to conduct studies to help the permitting authority determine what site-specific entrainment mortality controls, if any, will be required. This process will include public input.
  • New units at an existing facility that are built to increase the generating capacity of the facility are be required to reduce the intake flow to a level similar to a closed cycle, recirculation system. Closed cycle systems are the most effective at reducing entrainment, says the EPA. This can be done by incorporating a closed-cycle system into the design of the new unit, or by making other design changes equivalent to the reductions associated with closed-cycle cooling.

Sources of delay in issuing the new rule have included the need to take into consideration the impacts of cooling water intake structures on endangered aquatic species, under an agreement with environmental group Riverkeeper, and the 2013 US government shutdown.