Operational, water quality and temporal factors affecting impingement of fish and shellfish at a Texas coastal power plant

The Barney M. Davis Power Plant in Corpus Christi, Texas, withdraws large quantities of water from the Laguna Madre for non-contact cooling. As a result, fish and shellfish may be harmed when impinged against screens intended to remove debris and wrack (floating sea grass). To reduce impingement it is important to understand related factors and their interrelationships. Several operational, water quality, and temporal factors were correlated with the total number of impinged organisms when the plant is pumping water. In this study, operational factors included hourly average flow and the number of screens in operation during sampling. Water quality factors included temperature, dissolved oxygen, pH, conductivity and salinity. Temporal factors included month and time of day of impingement sampling. Over the course of a year, fish and shellfish impinged on Passavant traveling drum screens were collected, classified, and counted. Multiple regression analyses were conducted and the number of organisms impinged was the response variable. Total impingement was most associated with dissolved oxygen concentration, sampling month and sampling time. For fish, sampling month and dissolved oxygen were most associated with impingement, while for shellfish, sampling month and sampling time were most important. Hourly flow and number of operating screens were not significant predictors of impingement.