This polygon shapefile depicts the estimated extent of power plant entrainment in the Southern California Bight. Included in the attributes is scale range of larvae entrained per year. The attributes also include the offshore distance and the alongshore distance that is affected by entrainment. The entrainment area calculations are based on several assumptions, including (1) that alongshore extent is 5-times cross-shore extent, (2) bottom depth slopes linearly to about 10m at the outer edge of this entrained volume, and (3) the entrainment area appears on both sides of the intake as currents may run in one direction or the other. Where the intake is in an enclosed bay, this area extends beyond the bay when the bay holds less volume than that pumped in a 10-day period (e.g., Alamitos Bay), or is confined to the bay where the bay is large enough (e.g., San Diego Bay). This is a simplified approach and a more detailed assessment should be developed for any specific site that may interact with nearby marine protected areas. The reference used to create this shapefile: Foster, M., Steinbeck, J. 2008. Compilation of California coastal power plant entrainment and impingement estimates for California State Water Resources Control Board staff draft issue paper on once-through cooling. California State Water Resources Control Board. This coverage displays the estimated extent of area affected by power plant entrainment in the Southern California Bight, the curved coastline of Southern California between Point Conception and San Diego. Entrainment is a process by which small aquatic organisms are carried by the cooling water into a power plant and assumed killed by heat, turbulence and/or chemicals. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.