they may produce serious cumulative encroachment upon available and irre- 

 placeable estuarine habitats. 



Lacking sufficient knowledge in specific areas concerning species 

 utilization or hydrological effects, we can usually only recommend the 

 maintenance of existing conditions. 



Recognizing the above problems, program personnel during the 

 past year and under the present system of coordination with the Branch of 

 River Basin Studies nnade 180 appraisals of engineering projects potentially 

 affecting estuarine fishery resources. Of this number, all but six involved 

 Texas waters. The majority of these resulted from more than 325 Corps of 

 Engineers public notices and letters received during the year and screened to 

 determine which projects could materially affect estuarine and marine fishery 

 resources. Sections pertaining to these fishery resources in 40 Bureau of 

 Sport Fisheries and Wildlife draft reports were also reviewed. 



Evaporation losses from irrigation 

 ditches may reduce necessary fresh- 

 water inflow to estuaries. 



54 



