Weeki Wachee River System Recommended Minimum Flows and ...

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Determining a low flow need during a high flow period is virtually impossible. This accounts for much of the problem with the District’s evaluations of fish and invertebrates. The District used 16 of the best or most applicable sets of results to establish flow reductions that met threshold criteria for freshwater habitat, salinity habitat, benthos and mollusks. In addition, the District presents a graphical summary of the results that includes 32 measures of resource loss due to streamflow reductions. Several of these, particularly those that are most conservative, involved extrapolations beyond the river reach of concern, including some extrapolations into the Gulf of Mexico. Because they are beyond the domain of the regressions, or were biased by high flow study conditions, the District decided to base the MFL for the WWRS on the mean percentof-flow reduction allowed for seasonal Block 1 (10.1 % flow reduction) and seasonal Block 3 (10.7% flow reduction). In the end, the District recommended that both the wet and dry season flows for the WWRS be maintained at 90% of the baseline (read: naturalized) flows after the effects of human usage have been eliminated from the flow record. The fact that existing human usage is presently at or near the 10% limit means that little or no additional flow reductions will be allowed. After review, the Panel concurs with this recommendation. 4
Scientific Peer Review of the Proposed Minimum Flows and Levels for the Weeki Wachee River System INTRODUCTION The Southwest Florida Water Management District (the District) is mandated by Florida statutes to establish minimum flows and levels (MFLs) for certain surface waters and aquifers within its boundaries for the purpose of protecting the water resources and the ecology of the aquatic ecosystems from “significant harm” (Florida Statutes, 1972 as amended, Chapter 373, §373.042). What constitutes “significant harm” is not legally defined by the statutes; therefore, the Panel believes that one purpose of the District’s MFL report should be to define it scientifically. The District implements the statute directives by annually updating a list of priority water bodies for which MFLs are to be established and identifying which of these will undergo a voluntarily independent scientific review. Under the statutes, MFLs are defined as follows: 1. A minimum flow is the flow of a watercourse below which further water withdrawals will cause significant harm to the water resources or ecology of the area; and 2. A minimum level is the level of water in an aquifer or surface water body at which further water withdrawals will cause significant harm to the water resources of the area. Revised in 1997, the Statutes also provide for the MFLs to be established using the “best available information,” for the MFLs “to reflect seasonal variations,” and for the District’s Board, at its discretion, to provide for “the protection of nonconsumptive uses.” In addition, §373.0421 of the Florida Statutes states that the District’s Board “shall consider changes and structural alterations to watersheds, surface waters and aquifers, and the effects such changes or alterations have had, and the constraints such changes or alterations have placed on the hydrology of the affected watershed, surface water, or aquifer….” As a result, the District has identified a baseline condition that realistically considers the changes and structural alterations in the hydrologic system when determining MFLs. 5
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Weeki Wachee River System Recommend
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Conversion Table Metric to U.S. Cus
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5.2 FISH ..........................
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Figure 3-2 Location of Bathymetric
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LIST OF TABLES Table 1-1 Rule-of-Th
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Table 8-1 Summary of Weeki Wachee M
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Executive Summary Minimum Flows and
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CHAPTER 1 - PURPOSE & BACKGROUND OF
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1) flood flows that determine the b
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the area." What constitutes "signif
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Table 1-1 Rule-of-Thumb Estimates f
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this report identifies specific res
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1.6 Content of Remaining Chapters I
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CHAPTER 2 - WATERSHED CHARACTERISTI
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# # # circular vent 1.8 meters in d
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Figure 2-5 1970s Aerial with 1999 U
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is a variation of the Seminole word
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Figure 2-6 Hurricane Tracks near Ba
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varied by period. The variation was
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2.3.2 Baseline Period Figure 2-10 i
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found (ktau p=0.06) between total g
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similarly across the springsheds ex
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Figure 2-15 Wavelet Filtered Discha
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Figure 2-16 INTB Groundwater Model
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2.6 Seasonal Blocks As described in
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Table 2-6 Median (cfs) Flow by Bloc
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# # # Surface waters in this stretc
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3.1.3 Segmentation Segmentation was
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Figure 3-5 Dominant SAV and Median
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Figure 3-6 Sediment Characteristics
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Figure 3-7 Shoreline / Buffer Veget
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CHAPTER 4 - TIDE, SALINITY & WATER
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Two additional harmonic pairs were
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Figure 4-5. Median Bottom Salinity
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Figure 4-7 Salinity Range (1984-200
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uncovering in response to strong wi
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E) Salinity = β o + β 1 *Flow 2 +
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Additional exploratory attempts usi
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86 = 186 cfs, SWFWMD 1994-96 = 167
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A regression of the form below was
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Table 4-8 Median Water Quality of W
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Figure 4-10 Nitrate Concentration a
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CHAPTER 5 - BIOLOGICAL CHARACTERIST
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Figure 5-1 Principal Component Anal
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measured volume sampled which was t
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5.2.2 Relation to inflow Response t
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Table 5-7 Location Response (km u )
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Table 5-9 Abundance Response to Inf
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animals can survive chronic exposur
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Figure 5-3 Number of Aerial Manatee
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Figure 5-5(a) Molluscan Presence /
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Table 5-11 Rank Order of Mollusc Ab
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Figure 5-5 Polymesoda caroliniana A
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Figure 6-1 Plankton Tow Flows Compa
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In application, a baseline area and
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6.1.4 Benthos Protection for benthi
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Figure 6-3. Location of the Three P
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7.2 Manatee Approach Establishing a
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Figure 7-2 Joint Probability of Occ
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Figure 7-3 Maximum Day Manatee Usag
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Figure 7- 6 Example Calculations fo
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Figure 7- 7 Estimation of Flow Redu
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Figure 7-8. Summary Results for the
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The reductions in flow that meet th
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probably accounts in part for the d
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Postel, S. and B.Richter. 2003. Riv
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Stanford, J.A., J.V.Ward, W.J. Liss
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Culter, J.K. 1986. Water Chemistry.
Page 138 and 139: CHAPTER 10 - APPENDICES 10.1 Append
Page 140 and 141: The wavelet used is the symmlets wa
Page 142 and 143: explains, the energy plot shows the
Page 144 and 145: 0 if no significant withdrawal Z =
Page 146 and 147: One advantage of using this regress
Page 148 and 149: Technical Memorandum January 22, 20
Page 150 and 151: Lecanto 1 & 2 #S Well Site Descript
Page 152 and 153: Figure 4. HSPF subbasins in the INT
Page 154 and 155: Most of the limestone mines located
Page 156 and 157: 3.1.3 Septic Tank Recharge in the S
Page 158 and 159: Figure 10. Groundwater grid in the
Page 160 and 161: Basso, R.J., 2004, Hydrogeologic Se
Page 162 and 163: 10.2 Appendices - Chapter 3 Appendi
Page 164 and 165: 10.3 Appendices - Chapter 4 Appendi
Page 166 and 167: Appendix 4-2 Data Sources Water qua
Page 168 and 169: Appendix 4-3 Water Quality Trend Gr
Page 170 and 171: Water Quality Trend Graphics, conti
Page 180 and 181: United States Department of the Int
Page 182 and 183: October 8,2008 Florida Fish and Wil
Page 184 and 185: Martin Kelly, Ph.D. Page 3 October
Page 186 and 187: Scientific Peer Review of the Propo
Page 190 and 191: Current state water policy, as expr
Page 192 and 193: Spring, Twin Dees Spring and possib
Page 194 and 195: under varying flow regimes. The fir
Page 196 and 197: Weeki Wachee Rainfall, Springflow a
Page 198 and 199: 6.0 Discharge:Precipitation (cfs/in
Page 200 and 201: Nevertheless, a major concern with
Page 202 and 203: system grid is not totally orthogon
Page 204 and 205: In a hydrodynamic model study, one
Page 206 and 207: analysis was rather cursory. The Di
Page 208 and 209: (taxa) richness in the WWRS. If the
Page 210 and 211: Freshwater Habitats Approximately 1
Page 212 and 213: ERRATA and EDITORIAL COMMENTS Page
Page 214 and 215: Page Paragraph Line Comment 14 Some
Page 216 and 217: Page Paragraph Line Comment 21 The
Page 218 and 219: Page Paragraph Line Comment 26 The
Page 220 and 221: REFERENCES Alber, M. 2002. A Concep
Page 222 and 223: Richter, B. D., J. V. Baumgartner,
Page 224 and 225: the regression equation used to pre
Page 226 and 227: and the three independent approache
Page 228 and 229: The Southwest Florida Water Managem
Page 230 and 231: the model in terms of tides, salini
Page 232 and 233: Attachment 1 - Comparison of salini
Page 234 and 235: Figure 1. Predicted drawdown (feet)
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