size and speed, and canal dimensions. Continued high turbidity levels 

 may inhibit phytoplankton and submergent plant productivity within canals. 



Ordinarily the effect of facility placement on waterflow patterns is minor 

 compared to the hydrologic variations resulting from annual river dis- 

 charge pulses and alterations generated during site access phases. The 

 small processing complex is but a minor component of a much larger altera- 

 tion-generating process. The pad may cause restricted changes in water 

 depths, water inflow, and turnover which subsequently cause localized 

 changes in plant composition, but such events are of minor consequence at 

 the ecosystem level of consideration. 



Disturbances associated with drilling and operation activities, vehicular 

 traffic, human presence, and noise initially cause short-term wildlife 

 displacement which may become permanent displacement if the wellsite or 

 unmodified marsh is converted for long-term production. Nearby resting, 

 foraging, and escape cover are degraded by the proximity of continuous 

 human activity and operational procedures. Sensitive wildlife species 

 avoid otherwise favorable habitats because of human intrusion into 

 formerly undisturbed environments; notable examples are abandonment of 

 nesting rookeries by wading and shorebirds and reduced use of favored 

 feeding areas by waterfowl. The magnitude of such displacement, though 

 difficult to predict, should be recognized as an important consideration 

 which extends project impacts beyond the boundaries of the immediate 

 site. 



Key attribute alterations 



The key attribute alterations associated with production phase activities 

 involve primarily the direct long-term removal of productive plant assem- 

 blages and those directly dependent consumer groups residing within the 

 production/treatment complex site. Consumer response is a function of 

 the areal extent of the change, the size of the consumer's resource base, 

 and its sensitivity to altered habitat conditions. Sensitive wildlife 

 species may abandon otherwise favorable habitats because of continuous 

 operational and vehicle-associated disturbances. 



Changes in land elevation generate changes of waterflow that can lead to 

 erosion losses of marsh substrates and vegetation. Strategic placement 

 of spoil could compensate for subsidence and lead to a net increase in 

 land elevation and readjustments of local flow patterns. Alterations 

 will eventually elicit long-term changes in vegetative cover, followed by 

 appropriate changes in consumer composition. 



The chronic effects of persistent toxic materials, particularly brine, 

 may be more important than acute effects on local biotic assemblages. 



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