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health considerations, and that there may be no damage at all to the 

 shellfish habitat, particularly if the waste is treated domestic sewage, 

 which contains excellent nutrients for shellfish. 



Recreation as a restrictive impact 



Liquid wastes may have restrictive impacts on both body contact 

 and non-contact forms of recreation. The invisible dangers of water- 

 borne pathogenic organisms are as important in restricting recre- 

 ational use as the floating scum and oil which damage aesthetic quality 

 and cause people to go elsewhere. 



Recreational use is never entirely eliminated. Even around the most 

 polluted estuarine areas can be found an occasional fisherman or boat- 

 ing enthusiast. The people who cannot go elsewhere will use their local 

 estuarine zone in whatever fashion is possible, even if there is a public 

 health danger or the environment is unpleasing. The dangers inherent 

 in such use fall primarily on children, who tend to play in any avail- 

 able puddle, not caring whether it is the local swimming hole or New 

 York harbor. 



Water supply as a restrictive iTnpact 



The use of estuarine waters for municipal and industrial process 

 water supplies is not extensive because its primarily brackish quality 

 makes it difficult to treat adequately and economically. Estuarine 

 waters are used extensively for industrial cooling water use, and waters 

 with suspended solids, high acid of alkali concentrations, or high 

 nutrient concentrations are difficult to use. Such waters clog screens, 

 corrode pipes, or develop slimes which require added maintenance 

 expense. 



With increasing population and industrial growth in many coastal 

 areas and increasing demands for potable and industrial process water, 

 the use of fresh estuarine waters for water supplies may become an 

 important estuarine water use. Fresh waters in the estuarine zone 

 occur near where the rivers reach sea level, and it is here at the natural 

 head of navigation that many of the large ports are located and dis- 

 charge their wastes. 



Oom/mercial fishing 



Some kinds of commercial fishing require the use of trawls or the 

 setting of traps or nets that must be left for some time. The use of such 

 devices restricts other uses while the devices are in place, but there is 

 no permanent appropriation of estuarine waters or space. The major 

 conflict is with recreation in that recreational boating must be excluded 

 from areas where fishing gear is near the surface. 



Shellfishing is restrictive in the sense that commercial oyster and 

 clam beds require the waters above them to be of far better quality 

 than is required for safe body contact. This has been a significant 

 impact up to the present only in that waste treatment requirements of 

 some municipal and industrial wastes have had to be set higher than 

 would otherwise be necessary. With increasing numbers of watercraft 

 in estuarine waters the potential additional human wastes from these 

 boats may require restriction of some waters to recreational traffic in 

 order to protect shellfish beds. 



