Weeki Wachee River System Recommended Minimum Flows and ...

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Spring, Twin Dees Spring and possibly Salt Spring and Mud Spring, depending on land ownership. The District should consider revising this document in such a way that it covers the MFLs for the appropriate springs as well as the river and estuary. Clearly, the work that’s been done relative to the river includes the majority of the scientific information necessary for a Weeki Wachee Spring MFL. The additional information needed to address MFLs for the springs themselves may be relatively minor. In fact, additional investigations may be limited to evaluation criteria for (1) maintenance of groundwater flows for contact recreation at Weeki Wachee Spring and (2) the relationship of groundwater flows to nitrogen enrichment of the river. The latter issue is included because most Florida springs show a positive correlation of nitrate and spring discharge, so maintenance of flow cannot always be used for control of this nutrient. Public perception is often the opposite; therefore, a discussion of nutrients and their relationship to flow is recommended. In the end, the MFLs for Weeki Wachee and the other springs will probably be based on their contributions to flow in the river itself. This is implied in the District’s report (page 36, SWFWMD 2008) that states “the MFL for the Weeki Wachee, expressed as an allowable percent reduction, will be applied to the Weeki Wachee estuarine system which includes Mud and Salt springs.” The Panel notes that Twin Dees Spring is not mentioned here, but apparently should be. The quantity, quality and timing of freshwater input are characteristics that define an estuary. Freshwater inflows affect estuarine (tidal) areas at all levels; that is, with physical, chemical and biological effects that create a vast and complicated network of ecological relationships (Longley 1994). The effects of changes in inflows to estuaries are also described in Sklar and Browder (1998) and reviewed in Alber (2002). This scientific literature describes and illustrates how changing freshwater inflows can have a profound impact on estuarine conditions: circulation and salinity patterns, stratification and mixing, transit and residence times, the size and shape of the estuary, and the distribution of dissolved and particulate material, which may all be altered in ways that negatively affect the ecological health and productivity of coastal bays and estuaries. Inflow-related changes in estuarine conditions consequently will affect living estuarine resources, both directly and indirectly. Many estuarine organisms are directly linked to salinity: 8
the distribution of plants, benthic organisms and fishery species can shift in response to changes in salinity (Drinkwater and Frank 1994; Ardisson and Bourget 1997). If the distributions become uncoupled, estuarine biota may be restricted to areas that are no longer suitable habitat for their survival, growth and reproduction. Potential effects of human activities, particularly freshwater diversion and groundwater pumpage, on the adult and larval stages of fish and invertebrates include impacts on migration patterns, spawning and nursery habitats, species diversity, and distribution and production of lower trophic (food) level organisms (Drinkwater and Frank 1994; Longley 1994). Changes in inflow will also affect the delivery of nutrients, organic matter and sediments, which in turn can affect estuarine productivity rates and trophic structure (Longley 1994). There are a number of approaches for setting the freshwater inflow requirements of an estuary. The District has selected to use a “percent-withdrawal” method that sets upstream limits on water supply diversions and groundwater pumpage as a proportion of river flow. This links daily withdrawals to daily inflows, thereby preserving natural streamflow variations to a large extent. This type of inflow-based policy is very much in keeping with the approach that is often advocated for river management, where flow is considered a master variable because it is correlated with many other factors in the ecosystem (Poff et al. 1997; Richter et al. 1997). In this case, the emphasis is on maintaining the natural flow regime while skimming off flows along the way to meet water supply needs. Normally, regulations are designed to prevent impacts to estuarine resources during sensitive low-inflow periods and to allow water supplies to become gradually more available as inflow increases. The rationale for the District’s MFL, along with some of the underlying biological studies that support the percent-of-flow approach for the WWRS, is built upon the analyses previously performed on the Upper Peace River (SWFWMD 2002) as peer reviewed by Gore et al. (2002) and in other scientific literature summarized by Flannery et al. (2002). Setting minimum flow rules requires several steps: (1) setting appropriate management goals; (2) identifying indicators to measure characteristics that can be mechanistically linked to the management goals; (3) reviewing existing data and collecting new data on the indicators; and (4) assembling conceptual, qualitative, and quantitative models to predict behavior of the indicators 9
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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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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 188 and 189: Determining a low flow need during
Page 190 and 191: Current state water policy, as expr
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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