2.4 Increase in suspended sediments and dissolved nutrient concentra- 

 tions 



2.5 Alteration of modified circulation patterns as a consequence of 

 reestablishing former marsh flow regimes 



3. Attribute alterations 



Procedures which reestablish the surface contours existing prior to those 

 topographic alterations generated by canal dredging, levee and pad con- 

 struction, and pipelining activities, are most effective in restoring 

 basic site, as well as ecosystem, integrity. Flow patterns interrupted 

 by levees and diversion canals may be reestablished. Backfilling, canal 

 plugging, levee removal, and levee breaching procedures remove or alter 

 such obstructions to facilitate restoration of the original flow patterns. 

 Inherent properties of water covering the fresh marsh, such as average 

 water depth, frequency of inundation and exposure, and duration of sub- 

 mergence, effectively determine the nature of the dominant vegetation by 

 regulating the soil air regime and standing water depth. If standing 

 water depth is irregular and shallow, shallow-water emergents and wet- 

 meadow components dominate. Relatively deep permanent water encourages 

 dominance of floating and submergent components. Marsh fauna is deter- 

 mined by the dominant vegetation types. Several waterfowl species and 

 furbearers are attracted to particular sedges, rushes, and other emer- 

 gents as food plants and for cover requirements. Floating and submergent 

 species provide food for several waterfowl species and also support a 

 wide array of aquatic vertebrates. Rectification of alterations caused 

 by diking, ditching, and channelization helps restore initial water cir- 

 culation and intramarsh mixing patterns. 



Reworking levees, filling in canals and pits, and removing surface flow- 

 lines destroys small quantities of producer biomass that have become 

 established on such sites during the operational life of the facility. 

 Favorable cover types attractive to selected wildlife species, such as 

 that found on levees, may be lost during restoration procedures. Canal 

 levees, once vegetated with woody growth (primarily Baccharis spp. and 

 Iva spp.) are used by many species of mammals, birds, and reptiles. 

 Suspended sediments associated with such earthwork, combined with subse- 

 quent runoff from exposed substrates in the activity area, increase water 

 turbidity levels. Depending on site location and project magnitude, and 

 effects may be restricted to the immediate site or extended over larger 

 areas. Plugging and/or filling ditches, canals, and other openwater cuts 

 removes existing or potential aquatic environs for such consumer groups 

 as the aquatic invertebrates, fish, alligator, waterflowl, and some wading 

 birds species. Knocking down mound substrates and reestablishing former 

 survace contours, however, may reform surface depressions and low sites 

 for the same consumer groups. 



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