Tavernier Creek.” Thus, Halley (2002) described the potential increase in turbidity as “simply a natural response to creating a bay more like the one that existed at the turn of the century.” This vision, however, is different from the view that associates pristine conditions in the Bay with clear water.

This chapter first examines anticipated changes in patterns of freshwater inflows to the Bay under the CERP, and then considers whether these changes, which are designed to lessen the likelihood of hypersaline conditions developing in the Bay, may be undermined by the accompanying influx of nutrients.

Freshwater Inflows to the Bay

Simulating past, present, and future freshwater inflows to Florida Bay is challenging due to the large number and tidal nature of the creeks that drain the coastal mangrove zone, and to poor linkages between Everglades and Florida Bay models (see Chapter 3). Some flow measurements are now being made (e.g., Hittle et al., 2001), but flows are more commonly modeled. To date, the Natural System Model (NSM) has been the primary tool for simulating the hydrologic behavior of the pre-drainage Everglades. The South Florida Water Management Model (SFWMM) has been used to simulate the system infrastructure and operations as they are currently (“1995 Base”), as they will be in 2050 without any CERP projects in place (“2050 Base”), and as they could be in 2050 with CERP projects completed (“D13R”). The models are discussed in Chapter 3, and the model runs are described in more detail in Appendix B.

Taylor Slough and Craighead Basin

Direct fresh surface water flow into Florida Bay occurs primarily through Taylor Slough and, to a lesser extent, Craighead Basin. These modeled flows are shown in Figure 3. Slightly to the east, southward flow through the C-111 canal to the Eastern Panhandle area of Everglades National Park (Figure 3, right-most set of bar graphs) also occurs. Most of this flow, however, does not end up in Florida Bay. Rather, it is discharged east of U.S. Hwy 1, eventually passing into Barnes Sound and thence northeastward through Card Sound to Biscayne Bay. Very minor quantities of Eastern Panhandle water discharge to northeastern Florida Bay through the degraded C-111 embankment (Richard Punnett, USACE, Personal commun., July 2002).

From Figure 3 it can be seen that more water flows into the Eastern Panhandle under the 1995 Base or “current condition” relative to the NSM simulation. This is reduced under alternative D13R4 (a scenario based on D13R that would capture additional water “lost” to tide). The surplus (119,000-50,000=69,000 acre-ft per year (8.5x107 cubic meters per year) would be redirected upstream into Shark River Slough and downstream to a very small degree into Craighead Basin and Taylor Slough, in an effort to replicate NSM flows (although CERP flow targets may differ from NSM estimates). Hence, simulated fresh surface water flows to Florida Bay through Craighead Basin and Taylor Slough increase only minutely from 32,000+94,000=126,000 acre-ft per year (15.5x107 cubic meters per year) under the 1995 Base scenario to 45,000+82,000=127,000 acre-ft per year (15.6 cubic meters per year) under the D13R4 scenario. The Taylor Slough flow under the D13R4 scenario would be close to the NSM-estimated flow shown in Figure 3.



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