Section 316 of the Clean Water Act

316(a) Thermal Regulations

Section 316(a) of the Clean Water Act regulates heated discharges into waters of the United States.

Relevant Documents

316(b)Cooling Water Intake Structure Regulations

EPA developed new regulations issued in 2014 under section 316(b) of the Clean Water Act that are of great significance to the owners and operators of many power plants within Maryland, and also to electricity consumers within our state. Section 316(b) requires that the location, design, construction and capacity of cooling water intake structures reflect the best technology available (BTA) for minimizing adverse environmental impact. The withdrawal of cooling water has the potential to cause environmental impacts due to impingement and mortality of organisms, primarily fish, on screens that protect the intake system, and through entrainment and mortality of small organisms, primarily fish eggs and larvae, that pass through those screens and through the plant’s entire cooling system. Development of the regulations originally took place in three phases: Phase I, which was completed in late 2001, applied to new facilities. Phase II, which was issued in 2004, consisted of regulations applicable to existing large facilities, defined as those withdrawing more than 50 million gallons of cooling water per day (mgd). Phase III consisted of regulations applicable to small existing facilities (i.e., those that withdraw less than 50 mgd). In 2007, the U.S. 2nd Circuit Court of Appeals decided in Riverkeeper, Inc., v. EPA that many parts of the Phase II rule were invalid or needed to be reevaluated by EPA. Thus, in 2007, the Phase II rule was suspended. A portion of this ruling with respect to the cost-benefit test was appealed to the U.S. Supreme Court. The court ruled in 2009 that the cost-benefit test is allowed; specifically, the court stated: “The EPA permissibly relied on cost-benefit analysis in setting the national performance standards and in providing for cost-benefit variances from those standards as part of the Phase II regulations.” EPA issued a proposed revised rule for public comment in 2011, addressing the other issues required by the Riverkeeper case and the U.S. Supreme Court ruling on cost-benefit testing. PPRP submitted comments on the proposed rule. The EPA finalized the standards effective October 14, 2014 and further details are available at USEPA's 316(b) website.

Consequences for Maryland Power Plants

There are 7 existing power generating facilities in Maryland that have permits allowing for cooling water withdrawals greater than 2 mgd and which are covered by the new rule. All of these facilities had 316(b) demonstration studies conducted in the late 1970's or early 1980's and all were eventually found to be in compliance with Maryland’s 316(b) requirements. In order to attain compliance, some facilities were required to conduct additional studies to determine the extent of their entrainment and impingement (E&I) impacts and one (Chalk Point) was required to mitigate its impacts.

As an EPA-delegated state, in the late 1970s Maryland developed and implemented regulations of cooling water withdrawal and intakes in accordance with EPA guidance on implementation of Clean Water Act Section 316b provided at that time. Code of Maryland Regulations (COMAR) established procedures for determining adverse environmental impacts due to impingement and entrainment at cooling water intake structures, relative to determination of BTA for minimizing these impacts. These regulations were based on scientific and technical knowledge of the factors influencing the type and magnitude of impacts expected to occur, and followed a logical conceptual framework.

The basic elements of that framework include:

  • the evaluation of entrainment impact to a specified level of biological significance; i.e., representative important species (RIS) and spawning and nursery areas of consequence for the RIS
  • a determination of the significance of the entrainment impact that is based on the extent to which the direct effects of the CWIS impact the viability of the RIS population and/or the ecosystem necessary to support its life history functions; the direct effect of the cooling water intake (i.e., the number of fish impinged or entrained) is not the major focus of our regulations; it is the consequence of that effect to the biological entity of concern, whether at the species or the ecosystem level, that establishes what actions the state will take
  • a determination of BTA for impingement based on a simple cost/benefit analysis, comparing the value of fish lost to impingement to the cost for intake restructuring

Since the new rule has been finalized, Maryland will be required to ensure that Maryland’s regulations are consistent with federal regulations. Many of the concepts incorporated by EPA into the new final rule have substantial consequences to the types of cooling water intakes that would be legal for power generating facilities in Maryland, which are of significance to both the owners of the facilities as well as electricity consumers in the state. NPDES permits issued in accordance with the 2014 EPA rule are requiring additional studies on entrainment and impingement impacts, along with economic and engineering studies needed to comply with the rule. Reports on these studies will be due starting in 2020.