Use of Trawl Sampling to Assess Entrainment Affects in an Estuary

The U. S. Environmental Protection Agency’s regulations for implementing § 316(b) of the Clean Water Act became effective on October 14, 2014.  The § 316(b) rule establishes requirements for determining the Best Technology Available (BTA) for reducing the impingement and entrainment of aquatic organisms at cooling water intake structures.  The state permitting agency must make a site-specific determination of BTA for entrainment based on several factors.  In addition, the permitting agency may consider entrainment impacts on the water body.  Duke Energy’s Brunswick Nuclear Station is located on the Cape Fear River Estuary, NC.  Trawl sampling was initiated in the tidal marsh nursery areas adjacent to the intake canal and upriver of the station during January 2015 to assess recruitment of ocean spawned species to these nursery areas. The objectives of the trawl study are to collect information regarding species composition, relative abundance, and spatial distribution.  Results can be compared to data collected from 1981 to 1993.  Historical results indicated that once-through cooling water withdrawal from the estuary had no detectable effect on the organisms recruiting to the estuarine nursery areas.  Data collected during 2015 will provide an assessment of existing recruitment patterns and abundance.