different years are attributed to 

 differences in the total rainfall 

 during the two periods (Schneider 

 and Waller 1980), rather than to an 

 effect of drainage. 



In 1979 the National Park Ser- 

 vice and the U.S. Army Corps of 

 Engineers agreed that 37,000 acre- 

 feet of water per year would be sup- 

 plied to upper Taylor Slough through 

 pumping station S-332, to be instal- 

 led on canal 3I-W. It is expected 

 that the new flow regime will result 

 in significant changes in the hy- 

 drology and vegetation of the slough 

 below this point. Additional infor- 

 mation on hydrologic conditions, 

 such as approximate hydroperiods, in 

 the lower slough prior to flow aug- 

 mentation are presented by Olmstead 

 et al. (1980) in association with 

 vegetation distributions. 



Considerable effort has been 

 expended in recent years to charac- 

 terize the impact of land use and 

 drainage activities on surface and 

 groundwater quality in upper Taylor 

 Slough (DERM 1980). With the excep- 

 tion of samples taken in a borrow 

 canal which taps the saline Floridan 

 Aquifer, concentrations of major 

 inorganic ions and specific conduc- 

 tance are generally lower in Taylor 

 Slough than in the Shark River 

 Slough to the north. Background 

 specific conductance in Shark River 

 Slough is around 400 uohms/cm* 

 while to the south, in Taylor 

 Slough, values are slightly lower 

 (Waller 1979). At the borrow canal 

 station, distinct seasonality is 

 apparent in specific conductance due 

 to the relative diluting influence 

 of Shark River overflow during the 

 wet season. 



Macronutrients at both canal 

 and marsh sites within Taylor Slough 

 are low. Organic carbon is rela- 



tively lower in Taylor Slough sui — 

 face waters than in Shark River 

 Slough, presumably because of the 

 less organic marl soils in the 

 former. As ponding occurs during 

 the dry season there is a tendency 

 for nutrients and inorganic ions to 

 increase in concentration. 



5.6 FLORIDA BAY 



The freshwater drainage to 

 Florida Bay is limited to runoff 

 from Taylor Slough, runoff from the 

 coastal wetlands south of the main 

 Shark River Slough, and groundwater 

 seepage from the mainland. Thomas 

 (1974) has shown that the inverse 

 relationship between the height of 

 the groundwater table and salinity 

 in northern Florida Bay is a fairly 

 linear one. 



Due to its restricted flushing, 

 water levels in Florida Bay may 

 fluctuate by as much as 53 cm (21 

 in) seasonally (Turney and Perkins 

 1972). During hurricanes, water 

 depths have been observed to in- 

 crease as much as 3.7 m (12 ft) in 

 western Florida Bay and 1.2 to 1.5 m 

 (4 to 5 ft) in the northern bay 

 (Ball et al. 1967). 



Based on the distribution of 

 benthic mollusks, Turney and Perkins 

 (1972) divide Florida Bay into four 

 subenvironments (Figure 36): 



(1) The northern subenvironment 

 near the mangrove coast; 



(2) The interior subenvironment, 

 encompassing the northeast- 

 ern half of the bay; 



(3) The Atlantic subenvironment, 

 beginning at the middle Keys 

 and running along the back 

 of of the reef tract; and 



(4) The Gulf subenvironment, 

 just inside the 1.8 m (6 ft) 

 contour between Cape Sable 

 and Fiesta Key. 



83 



