bulkheads, ditches, and transmission lines are discussed in other 

 subprojects. 



4.7 ARTIFICIAL WATERWAYS 



The land available and desirable for community growth in low-lying 

 coastal communities may require drainage before construction. Many 

 communities that would attract OCS onshore facilities are in low- 

 lying coastal areas with considerable water-soaked land. Drainage of these 

 near-wetlands and wetlands by canals and ditches 1s often proposed, as is 

 the excavation of lakes or canals and use of the material to fill the 

 adjacent land. Canals may be dug to provide boat channels back into the 

 land, or ditches may be dug to drain land for mosquito control. This 

 variety of activities can accompany housing, recreation, transportation, 

 and all other components of development in low-lying communities. 



Whatever the specific reason, canal, ditch, and artificial lake 

 excavation can have serious adverse effects. For example, when the 

 natural flow pattern is disrupted, the water-cleansing function of the 

 vegetation is reduced, and freshwater flow into the estuaries occurs in 

 surges. Moreover, drainage may cause shrinkage of organic soils and 

 subsidence of land and eliminate the critical ecological functions of 

 wetlands. The main solution is to avoid any uses of these lands that 

 require drainage. 



4.8 ROADWAYS AND BRIDGES 



Increased population and community growth that result from OCS 

 activities encourage construction or improvement of roadways. If enough 

 new traffic is generated, there will be a need for more highways and 

 accompanying bridges in addition to local roads. If this road expansion 

 requires crossing of tidal rivers, bays, or wetlands, there is a high 

 potential for adverse ecological effects. A particular problem is solid- 

 fill causeways that block the upper portions of estuaries; these blockages 

 lead to stagnation and eventually to total deterioration. Supports and 

 abutments can also have a partial stagnating effect on the cutoff portion. 

 Roadways may obliterate wetlands due to the filling for roadbeds and 

 approaches, channeling for equipment access, disposal of spoil, and blocking 

 of wetland tidal flows. Solutions lie in aligning roadways to avoid 

 wetland alteration and in protecting surface water flows. 



4.9 WATER SUPPLY SYSTEMS 



Communities have two major alternative sources of water: subsurface 

 (groundwater) and surface. In coastal areas, groundwater may be a 

 preferable source either because of a lack of fresh surface water, or the 

 presence of easily accessible aquifers. There are problems involving both 

 recharge and withdrawal of groundwater. Water diversion caused by paved 



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