Section 316(b) of the Clean Water Act: Cooling Water Intake Structure Regulations

Consequences for Maryland Power Plants

    There are 9 existing power generating facilities in Maryland that have permits allowing for cooling water withdrawals greater than 2 mgd and which would potentially be 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 Marylandís 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 Marylandís regulations are consistent with federal regulations. Many of the concepts incorporated by EPA into the new final rule could have substantial consequences to the types of cooling water intakes that would be legal for power generating facilities in Maryland, which would be of significance to both the owners of the facilities as well as electricity consumers in the state.

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This page was updated on October 12, 2016 .