pulse of rainfall/runoff recedes and 

 the rate of flow decreases, so too 

 do losses to transpiration and evap- 

 oration. The pulse may travel as 

 little as 8 to 10 km (5 to 6 mi) in 

 a year or as much as 32 km (20 mi) 

 depending on specific conditions. 

 Then, as the subsequent year's pulse 

 begins, what remains of the previous 

 year's pulse (usually below ground 

 by then) becomes replenished with 

 local rainfall and upstream drain- 

 age. Increased upstream flow from 

 the current year's pulse pushes last 

 year's even farther downstream, 

 eventually into the estuarine zone. 



The open water estuarine zone 

 of the western Everglades National 

 Park begins about 24 to 32 km (15 to 

 20 mi) southwest of the 40-Mile Bend 

 in Tamiami Canal. Beginning with 

 the numerous small creeks that form 

 the headwaters of the Shark River 

 estuary, the tidal ly affected brack- 

 ish water zone extends southwesterly 

 for approximately 32 km (20 mi) to 

 Ponce de Leon Bay. To the south of 

 the Shark River estuary, coastal 

 drainage into Whitewater Bay occurs 

 through a diffuse network of smaller 

 rivers, most notably the Watson, 

 North, and Roberts Rivers. To the 

 north of Shark River estuary, drain- 

 age to the gulf through the Harney 

 and Broad Rivers is not only local 

 but in part derives from the Shark 

 River Slough. North of the Broad 

 River, Lostman's 3ay signifies the 

 beginnings of the "back bay" zone 

 (White 1970) that extends northward 

 along the coast eventually grading 

 seaward into the Ten Thousand Is- 

 lands. This area is characterized 

 by a line of bays set back and sepa- 

 rated from the coast by a 3 to 8 km 

 (2 to 5 mi) wide strip of mangrove 

 swamp. Drainage into Lostman's Bay 

 and the Gulf of Mexico arises pri- 

 marily from the drainage area north 

 of Shark River Slough and adjacent 

 to the Big Cypress Basin. 



The upper end of Shark River 

 estuary, known as Rookery Branch, 

 exhibits wide seasonal fluctuations 

 in water level and salinity. As 

 local rainfall and upstream flow 

 increase during June to October, 

 water level rises and salinity 

 falls. Seasonal salinity variation 



in the Shark River estuary is great- 

 est at Rookery Branch and gradually 

 decreases toward Ponce de Leon Bay. 

 The relatively shallow depth, low 

 channel slope, strong wind, and 

 constant tidal flux results in a 

 generally well-mixed, homogeneous 

 water column in Shark River and 

 nearby estuaries. Tidal velocities 

 approaching 6.4 km per hr (4 mph) 

 have been observed in the lower 

 Shark River (McPherson 1971). 



Kolipinski and Higer (1969) 

 characterize Shark River Slough 

 within the National Park as rela- 

 tively unpolluted with respect to 

 nitrate, sulfate, calcium, dissolved 

 solids, and iron. Median values and 

 ranges for these parameters from 65 

 samples collected between December 

 1959 and September 1967 appear in 

 Table 15. 



PARAMET ER 



SHARK RIVER SLOUGH 

 CONCENTRATION 



Table 15. Selected water quality 



parameter concentrations 

 in Shark River Slough 

 (adapted from Kolipinski 

 and Higer 1969). 



79 



