Galveston Bay project: stormwater loading study




Turner Collie and Braden Inc.

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Turner Collie and Braden Inc.


This engineering study was made to determine the biochemical oxygen demand (BOD) loadings resulting from stormwater runoff into Galveston Bay and its adjoining estuaries. Galveston Bay and its arms form a 522-square-mile body of water having general natural depths of about seven feet in Galveston and Trinity Bays and five feet in East and West Bays. Approximately 10.7 million acre-feet of stormwater runoff is discharged annually into the Bay from its 23,370 square mile tributary area. This runoff has a pronounced influence on the biological and chemical characteristics of the Bay water. The BOD loading, due to the surface runoff, is estimated to average about 127 million pounds annually, of which approximately 15 to 20 percent normally occurs during the month of May. The available water quality data, obtained since 1970, analyzed in this study were obtained at irregular time intervals along the streams in the tributary watershed. In some instances, these data were not obtained at existing stream gaging stations nor correlated to streamflow. During periods of heavy storm rainfall over the contributing drainage area, the BOD loadings are of major significance. It is estimated that, under existing conditions, the maximum 24-hour inflow having a yearly recurrence interval will be about 189,000 acre-feet and will produce a BOD loading of about 2.5 million pounds.


25 pgs.


stormwater runoff, biochemical oxygen demand (BOD), water quality