all coastal marshes. Anticipated water demands 

 not related directly to the project, combined 

 with project diversions, would reduce by one- 

 half the average annual freshwater flow of 31.7 

 X lO" m"^ now reaching Texas estuaries. Fresh- 

 water flow into the Galveston Bay system 

 would be reduced by about one-third. Even 

 more dramatically, Moore (1968) stated "It has 

 been roughly computed that annual freshwater 

 needs from the developed rivers for bays and 

 estuaries will amount to 2.45 million acre-feet 

 (3 X lO" m*^) annually, while the annual Gulf 

 water needs through new tidal inlets will 

 amount to 33.4 million acre-feet (40.7 x 10^ 

 m^)." This plan, if implemented, will cause 

 salinities in the Galveston Bay system to 

 increase. If freshwater inflows are reduced 

 without an increased flow of Gulf water into 

 the bay system, we anticipate nitrogen and 

 phosphorus concentrations to increase. If flow 

 of Gulf water into the bay system increases, we 

 anticipate nitrogen and phosphorus levels to 

 decrease. 



Hurricane protection levees are being built 

 around the Galveston Bay system and tidal 

 exchange structures for the tidal passes are 

 being designed and planned by the U.S. Corps 

 of Engineers. These structures are expected to 

 reduce tidal exchange, thus affecting the 

 normal circulation patterns in the system. 

 Salinities would probably be reduced under the 

 present stream flow conditions, whereas nitro- 

 gen and phosphorus levels would probably 

 increase owing to a reduction of water 

 exchange to the system. We would expect the 

 large amount of nutrients that would accu- 

 mulate to cause dissolved oxygen depletion of 

 the water at times. 



The quantity of industrial and domestic 

 effluents entering the Galveston Bay system is 

 about 1.8 million m"^ per day (R.A. Diener, 

 NMFS, unpublished data). Since human pop- 

 ulations are increasing rapidly in areas adjacent 

 to the Galveston Bay system, we expect the 

 domestic and industrial pollution load entering 

 the system to increase in a similar manner for a 

 long period of time. Nitrogen and phosphorus 

 levels are already high in some parts of the bay 

 system and are expected to reach much higher 

 levels in the near future. 



Various modifications to the bay system can 

 have opposing effects on particular hydro- 



graphic variables, as indicated in the examples 

 previously discussed. Some modifications could 

 be planned which allow the maintenance of 

 hydrological conditions similar to the natural 

 state. Until more is known about the biology 

 of estuarine animals, modifications of estuaries 

 without maintaining present hydrological 

 conditions involves a great risk of destroying 

 many valuable estuarine resources. 



LITERATURE CITED 



ARNOLD, E.L., R.S. WHEELER, and K.N. 

 BAXTER. 



1960. Observations on fishes and other biota 

 of East Lagoon, Galveston Island. U.S. 

 Fish Wildl. Serv., Spec. Sci. Rep. Fish. 

 344, 30 p. 



BALDAUF, R.J. 



1970. A study of selected chemical and 

 biological conditions of the lower Trinity 

 River and upper Trinity Bay. Water 

 Resour. Inst., Tex. A&M Univ., Tech. 

 Rep. 26, 168 p. 



CHAMBERS, G.V., and A.K. SPARKS. 



1959. An ecological survey of the Houston 

 Ship Channel and adjacent bays. Publ. 

 Inst. Mar. Sci., Univ. Tex. 6: 213-250. 



CHAPMAN, C.R. 



1966. The Texas Basins Project. In A sympo- 

 sium on estuarine fisheries, p. 83-92. 

 Amer. Fish. Soc. Spec. Publ. 3. 



CHIN, E. 



1961. A trawl study of an estuarine nursery 

 area in Galveston Bay, with particular 

 reference to penaeid shrimp. Ph.D. Thesis, 

 Univ. Wash., Seattle, 113 p. 



COPELAND, B.J., and E.G. FRUH. 



1970. Ecological studies of Galveston Bay, 

 1969. Final Report to Texas Water 

 Quality Board (Galveston Bay Study Pro- 

 gram) for Contract lAC (68-69)-408, Inst. 

 Mar. Sci., Univ. Tex., 482 p. 



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