The impacts of marinas on the water quality of Galveston Bay

Water quality impacts from marinas along the Gulf coast of the United States are poorly understood. It has been documented in other areas of the country that marinas with their associated boats can be a large source of pollutants, including heavy metals, fecal coliforms, and nutrients (NCDEHNR 1991). Improperly designed marinas can also reduce flushing and, during times of minimal water movements, concentrate pollutants and cause serious environmental harm, including fish kills. Galveston Bay and, in particular, the Clear Lake area contains a very high concentration of recreational vessels. Approximately 40 marinas with 9,171 wet slips were documented in Galveston Bay during 1987 (Ditton et al., 1988). This represents 62.9% and 29.9% of the total Texas coastal wet slips and marinas, respectively. Within the Clear Lake area alone there were an estimated 22 marinas with 6358 wet slips (Hollin, 1992). Until recently there were few locations to pump out boat sewage and, consequently, much of the boat sewage was directly discharged into Galveston Bay and/or Clear Lake. However, recently a private entrepreneur has built both portable and stationary sites in Clear Lake (Maritime Sanitation, 1992). Evaluating the impact of pollution from Galveston Bay marinas is the purpose of this project.