1-8 



of tidal influence to the measurable seaward effect of fresh 

 water runoff. This may vary in width from a few yards off 

 some parts of the California coast to fifty miles off the 

 Mississippi Delta. 



The geographic range of the social and economic estuarine envi- 

 ronment, the user's world, depends solely on man's ability and 

 need to get to and use the estuarine environment. In terms of 

 direct use, everything between the head of navigation landward 

 and in sight of land seaward would be included. 



The limits of the estuarine institutional environment are those 

 of the political subdivisions that include parts of the estua- 

 rine zone. This includes the 274 coastal counties, the 24 

 coastal States, the Territories, the District of Columbia, a 

 variety of interstate compacts and commissions, and the Federal 

 Government. 



The landward and seaward limits of the estuarine zone used in 

 this study were set for the purposes of collecting and analy- 

 zing information pertinent to the study. The limits do not 

 suggest that this zone can be isolated from either the upland 

 rivers or the ocean, nor that this zone can be managed effec- 

 tively without recognizing the problems in these and other 

 environments. 



