An Assessment of the Studies Used to Detect Impacts to Marine Environments by California's Coastal Power Plants Using Once-Through Cooling. This report prepared by Dr. Michael Foster's reviews the 21 coastal and estuarine power plants in California with a combined use of nearly 17 billion gallons of seawater daily for once-through cooling. The adequacy of existing studies to accurately determine the effects of this use of seawater on the marine environment is reviewed. The report evaluates how well impingement and entrainment impacts have been assessed for these 21 coastal and estuarine power plants in California, including those in the San Francisco Bay-Delta, that are currently operating using once-through sea water cooling systems.