water to flow around and through the rocks, but at a much slower rate. Flap gates allow more 

 control of water movement. Structural alternatives should be carried out in phases so that 

 monitoring and modification, if needed, can be implemented. 



We suggest that the spoil impounding the cypress swamp (site 18) be removed to promote 

 flushing and draw downs by aiding regeneration and establishment of seedlings (Figure 12). Water 

 levels and forest species composition and productivity should be monitored to determine the 

 ecological consequences of this action. 



To both slow rapid water level fluctuations in the wetlands and encourage overbank flow, three 

 water control structures should be installed: (1) in the Pipeline Canal, just north of its intersection 

 with the Segnette Waterway; (2) just west of the intersection of Tarpaper and the perpendicular 

 can^l flowing north of it; and (3) at the intersection of Kenta Canal and the Intercoastal Waterway. 

 Placement of the structure in Pipeline Canal would slow the flow of water out of the park and 

 enhance overland flow in both CTU 6 and 8, which currently show signs of hydrologic alteration. 

 Overland flow through CTU 2, 4, and 6 would be encouraged by the structure placed in Tarpaper 

 Canal. Removal of the spoil at the end of the northernmost oil cut on Segnette Waterway would 

 enhance waterflow out into Segnette and into Lake Salvador. These alterations would encourage 

 waterflow out of the park following both the natural wetland elevation gradient and the dampened 

 canal courses. 



These structural changes would establish and promote four types of flow through the park 

 (Figure 13): (1) upland runoff from the ridge into the park, (2) overland net flow through the 

 interior CTU (3) enhanced exchange between the lake water and the wetlands, and (4) diminished 

 water level fluctuations in the canals. 



(4) Freshwater and Sediment Diversions 



Freshwater and sediment diversions have been suggested as a means of nourishing wetlands 

 (Gosselink and Gosselink 1985; Templet and Meyer-Arendt 1988; Conner and Day 1987). 

 Wetlands act as buffers and filters for sediments and nutrients (Kennedy 1983; Howard- Williams 

 1985). Studies on effluent application to wetlands have shown that (1) long-term nutrient 

 accumulation occurs in some cases (Dixon and Kadlec 1975; Gupta 1977), (2) increased organic 

 matter and accumulation rates occur, and (3) that these nutrient and mineral sources are 

 incorporated into long-lived plant and animal matter (Gaudet 1977; Dolan et al. 1981; Verhoeven 

 et al. 1983; Howard-Williams 1985). Fresh marsh biomass increases significantly with nutrient input 

 (Dolan et al. 1981; Verhoeven et al. 1983). 



There are three potential sources for freshwater and sediment diversion into the park: (1) 

 resuspended sediments from Lake Salvador and local canals including the Intercoastal Waterway, 

 (2) nutrient and sediment sources from Millaudon Canal, and (3) Mississippi River water. The first 

 two sources would help offset the effects of subsidence and increase vegetation growth. Mineral 

 sediment inputs increase wetland elevation, enhance primary productivity, and increase organic 

 accretion in wetlands. 



Diversion into floating areas has never been attempted, and the consequences and methods are 

 yet to be determined. For example, would sediment accretion and productivity changes be more 

 substantial if sediment-laden waters were introduced above or below the floating mat? To answer 

 this question, a three-part experiment is suggested. Water should be pumped or diverted into two 

 separate regions~an area where water is introduced above the mat, and an area where the water 

 is introduced below the mat. There should also be a control where no water is pumped at all. 



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