Weeki Wachee River System Recommended Minimum Flows and ...

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(taxa) richness in the WWRS. If the salinities typically found in the downstream areas with fine sediments utilized by the benthic infauna were displaced upstream into areas with hard limestone substrates as a result of flow reductions, then the effects on the benthos would be magnified. Janicki Environmental (2007) also compiled and reanalyzed benthic data from samples taken in 12 tidal rivers in Southwest Florida over a 20+ year period of record using cluster analysis and principal components analysis. Univariate logistic regressions were used additionally to estimate the probability of species occurrence as a function of salinity. The resulting salinity optimums and tolerances for selected benthic species were considered in the District’s MFL determination, particularly in relation to flow reductions that could potentially reduce the availability of low (< 7 ppt, oligohaline) and medium (7-18 ppt, mesohaline) salinity habitats by more than 15%. Mollusks Mollusk surveys of the WWRS were conducted by Estevez (2005). While the total number of taxa found, only 15, was similar to that previously reported by Culter (1986), the overall species diversity and abundance in the WWRS is low, probably for the same reasons discussed above for the benthos; namely, oligotrophic waters and the prevalence of rocky substrates. Relative to 8 other tidal rivers along the west coast of Florida analyzed by Montagna (2006), the WWRS exhibits a fauna so depauperate that it makes analysis and interpretation of species data relative to flows and associated measures difficult and largely unsatisfactory. Nevertheless, Estevez (2005) suggests that significant reductions in flows could cause infilling of the lower river bottom with algae and other organic material that would create very unfavorable habitat conditions for mollusks and other benthic organisms. In the end, the District utilized significant relationships between salinity and the species abundance of two intertidal species (Polymesoda caroliniana and Littoraria irrorata) in the lower river, and the oyster (Crossostrea virginicia) at the mouth of the river, to compute a 15% loss of peak abundance for these species under reduced WWRS flows. 24
Fish and Planktonic Invertebrates Matheson et al. (2005) sampled fishes by seine and trawl, and planktonic organisms by plankton net from May 2003 through December 2004. Unfortunately, this sampling occurred during a period when WWRS flows were higher than the mean average flow for the prior 9 years. Determining a low flow need during a high flow period is virtually impossible. Further, this difficulty is enhanced by the fact that the estuarine portion of the river is very compressed and extends upstream less than 2 km (1.2 miles) from the river’s mouth under normal conditions. As a result, important fish species, such as the bay anchovy and sand seatrout that typically dominate fish assemblages in estuarine (tidal) river segments of the region, were in extremely low abundance in the WWRS. Zooplankton net samples were dominated by larval fishes (killifish, gobies and blennies) and larval invertebrates (crabs, shrimp and mysids). Matheson et al. (2005) report that planktonic invertebrates that were common in other tidal rivers of the region were uncommon or even absent in the WWRS, again probably because of the high flow period sampled. One interesting capture in the upper river involved two specimens of the rare mysid, Spelaeomysis, a species normally associated with underground aquifers. Invertebrate collections by seine in the WWRS were dominated by grass shrimp, daggerblade shrimp and blue crabs. The District attempted to relate fish and zooplankton abundance, and location of maximum occurrence, to flows in the WWRS; however, the results were generally weak with coefficients of determination below the District’s assumed acceptable threshold (i.e., r 2 ≥ 0.30). The most interesting significant positive relationship found was that between the abundance of harpacticoid copepods, which are prey (food) for young estuarine-dependent fishes, and 120-day lagged flows on the WWRS. Unfortunately, the fish and invertebrate analyses were not used by the District to determine the WWRS MFL because of the confounding high flows underlying the sampling period and the unusual or unreasonable responses suggested by most of the statistical regressions, including the predicted elimination of typical estuarine species under more normal (e.g., median) flow conditions. 25
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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.
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CHAPTER 10 - APPENDICES 10.1 Append
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The wavelet used is the symmlets wa
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explains, the energy plot shows the
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0 if no significant withdrawal Z =
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One advantage of using this regress
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Technical Memorandum January 22, 20
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Lecanto 1 & 2 #S Well Site Descript
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Figure 4. HSPF subbasins in the INT
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Most of the limestone mines located
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3.1.3 Septic Tank Recharge in the S
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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 188 and 189: Determining a low flow need during
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 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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