The Determination of Minimum Flows for Sulphur Springs, Tampa

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DRAFT Lastly, the relationship between the indicator and flow should be quantifiable, so that change in the indicator can be expressed and used in determining the minimum flow rates. The District determined there are three management goals important to the establishment minimum flows for Sulphur Springs, which are: (1) minimize the incursion of high salinity water from the river into the upper spring run; (2) maintain low salinity habitats in the Lower Hillsborough River; and (3) provide a thermal refuge for manatees in the Lower Hillsborough River. The rationale and ecological indicators corresponding to for each of these goals are presented below. This discussion is based on the information presented in Chapter 3 concerning the relationships of flow from Sulphur Springs to the ecology of the spring run and Lower Hillsborough River. 4.5 Goal 1 – Minimize the incursion of high salinity river water into the upper spring run. As discussed in Section 3.4, salinity data indicate that waters from the Lower Hillsborough River do not move into the upper spring run under normal flow conditions (no withdrawals). However, as flows are reduced by withdrawals, relatively high salinity water (up to 17 ppt) from the river can move into the upper spring run. Data collected by the FDEP and the FWC indicate that high salinity values that occurred in the upper spring run during the drought of 2000-2001 had a major impact on the macroinvertebrate community there, as a number of freshwater species were lost from the spring run. With the resumption of normal flows in late 2001, 2002 and 2003, a number of these species reappeared in the spring run, accompanied by increases in overall species richness, evenness, and diversity. A number of salt-tolerant species that persisted in the spring run during the drought also showed marked increases in abundance with the resumption of normal flows. Many of the species that rebounded with normal flows are important fish food organisms (isopods, amphipods, aquatic insects). Based on these findings, a goal of the District's minimum flow evaluation for Sulphur Springs is to minimize the incursion of high salinity river water into the upper spring run. This goal should provide suitable conditions for many of the freshwater taxa that have been found in the spring run, and maintain the high species richness and diversity that was observed during periods of normal flow. When there are no incursions of river water, salinity values in the upper spring run typically vary between 1 and 3 ppt on a seasonal basis. Given this salinity range, the upper spring run would not be classified as fresh water (
DRAFT It is the conclusion of this report that a threshold salinity value for the upper spring run would not be practical and should not be established. The wide array of species that inhabit the spring run during normal flow have different salinity tolerances. What is well documented is that the likelihood of high salinity values in the run increases as flows from the spring pool decline. Since it is directly related to flow, the ecological indicator that should be managed is the potential for salinity incursions as at function of flow. As will be described in Chapter 5, the frequency and duration of salinity incursions in the upper spring run increase as flows decline. To be most conservative, flows from the spring could be maintained at a rate that prohibits the incursion of river water and this option is discussed in Chapter 5. However, at some lesser rates of flow, salinity incursions are limited to only several hours on the days they occur. It is possible that many of the freshwater invertebrate species in the spring run could tolerate brief salinity incursions. However, useful values for durations of acceptable salinity exposure are not available from the scientific literature for the species in the spring run. Therefore, breakpoints in the flow-salinity relationship are evaluated in Chapter 5 and used to determine the potential for significant harm to the invertebrate community of the upper spring run and minimum flows for Sulphur Springs, It is concluded that macroinvertebrates represent a sensitive biological community in the upper spring run with regard to salinity. It is also concluded that minimum flows that prevent significant harm to the invertebrate community will also protect the shoreline plants and fishes as well. The plants that inhabit the spring run include species that are found in and along low-salinity reaches of tidal creeks and rivers (see discussion in following section). Sulphur Springs also provides a refuge for a number of freshwater fish species that inhabit the Lower Hillsborough River. As described in Section 3.8, the fish species documented by this study are among the more salt-tolerant freshwater taxa that are found in low salinity tidal creeks. However, the high salinity values that occurred during the 2000-2001 drought probably reduced the survivability of such species in the upper spring run. The frequency and duration of salinity incursions that are considered in the minimum flow analysis in Chapter 5 are well below the high salinity values that occurred during the drought. 4.6 Goal 2 - Maintain low salinity habitats in the Lower Hillsborough River In contrast to Sulphur Springs, the flow regime of the Lower Hillsborough River is characterized by high seasonal variability, ranging from prolonged periods of no flow at the dam to flow rates in excess of 1,000 cfs in the wet season. Compared to the spring run, the river encompasses a much broader salinity gradient that covers a wide range of salinity values. When there is discharge from the reservoir, salinity values range from fresh water (
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The Determination of Minimum Flows
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DRAFT TABLE OF CONTENTS List of Tab
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4.5 Goal 1 - Minimize the incursion
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DRAFT LIST OF FIGURES Chapter 2 - P
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Fig. 3-13 Fig. 3-14 Fig. 3-15 Fig.
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Fig. 5-7 Fig. 5-8 Fig. 5-9 Fig. 5-1
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Acronyms and Definitions DRAFT AMO
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DRAFT Executive Summary The Southwe
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DRAFT below 19 feet NGVD of 1929. T
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CHAPTER 1 PURPOSE AND BACKGROUND OF
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DRAFT water, or aquifer, provided t
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DRAFT one the indicators were the f
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DRAFT The spring and its run lie in
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DRAFT Figure 2-3. Recent photograph
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2 - 6 DRAFT
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DRAFT -5 -4 -3 -2 -1 0 1 2 3 0.4 4
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DRAFT 10.0 Yrly_Pumpage.grf 15 Annu
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DRAFT 1999 2000 2001 2002 2003 35 D
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DRAFT Figure 2-14. Return flow stru
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DRAFT 40 Jan. Feb. Mar. Apr. May Ju
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DRAFT due to withdrawals for public
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DRAFT Figure 2-19 . Temporal trend
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DRAFT Figure 2-20. Temporal trends
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DRAFT In comparison to specific con
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DRAFT average daily withdrawals for
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DRAFT Figure 2-25. Average specific
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DRAFT withdrawal rate of 31 cfs dur
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DRAFT Table 2-2. Sulphur Springs su
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DRAFT These plots indicate that his
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DRAFT CHAPTER 3 ECOLOGICAL RESOURCE
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DRAFT 3 Run_Riv_Stg.grf Water Surfa
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DRAFT 3.4 Salinity in the spring ru
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DRAFT 1999 2000 2001 2002 2003 2004
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DRAFT pumping events resulted in sa
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DRAFT As discussed in Section 2.5.3
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DRAFT tolerate and are frequently f
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DRAFT Appendix B are color coded to
Page 83 and 84: DRAFT habitat in the lower river pr
Page 85 and 86: DRAFT The FWC using a modified stra
Page 87 and 88: DRAFT increased with a return to no
Page 89 and 90: DRAFT 2000. The results from three
Page 91 and 92: DRAFT species (10 to 13) were colle
Page 93 and 94: DRAFT 1940 1950 1960 1970 1980 1990
Page 95 and 96: DRAFT . 1000.00 100.00 10.00 1.00 0
Page 97 and 98: DRAFT 3.9.2 The effects of flows fr
Page 99 and 100: DRAFT Data from the Tampa Bay Water
Page 101 and 102: DRAFT EPCHC Period of Record Data L
Page 103 and 104: DRAFT 35 30 1996 1997 1998 1999 200
Page 105 and 106: 7 DRAFT Elevation (m) 1 0 -1 -2 -3
Page 107 and 108: 8 24 25 29 DRAFT Figure 3-20, 3-21
Page 109 and 110: DRAFT Figure 3-22 HBMP & EPCHC 2000
Page 111 and 112: DRAFT of the river between the dam
Page 113 and 114: DRAFT 10 11 12 13 14 15 16 17 10 11
Page 115 and 116: DRAFT The HBMP project (PBSJ 2003)
Page 117 and 118: DRAFT xanthurus) red drum (Sciaenop
Page 119 and 120: DRAFT as manatees seek fresh water
Page 121 and 122: 1999 2000 2001 2002 DRAFT 35 TmpSS_
Page 123 and 124: DRAFT Platt Street 1974-2002 Columb
Page 125 and 126: DRAFT Median and minimum water temp
Page 127 and 128: DRAFT Figure 3-31 1999 2000 2001 20
Page 129 and 130: DRAFT Figure 3-33 2001 2002 2003 20
Page 131 and 132: DRAFT CHAPTER 4 TECHNICAL APPROACH
Page 133: DRAFT The sum of these consideratio
Page 137 and 138: DRAFT criteria. The
Page 139: DRAFT reach of the river 50 meters
Page 142 and 143: DRAFT of the dam. The experiments w
Page 144 and 145: DRAFT Salinity incursions above the
Page 146 and 147: DRAFT Figure 5-3. A - D. Box and wh
Page 148 and 149: DRAFT The results of the vertical p
Page 150 and 151: DRAFT Sulphur Springs < 33 cfs, Hil
Page 152 and 153: DRAFT Other breakpoints in the data
Page 154 and 155: DRAFT 40 Percent of Observations -
Page 156 and 157: DRAFT It is possible that infrequen
Page 158 and 159: DRAFT The effects of tide stage on
Page 160 and 161: DRAFT medians rise to near -0.2 fee
Page 162 and 163: DRAFT Sulphur Springs < 33 cfs, Hil
Page 164 and 165: DRAFT Sulphur Springs on salinity d
Page 166 and 167: 7 29 DRAFT Elevation (m) 0/0cfs 1 0
Page 168 and 169: 23 24 24 25 25 29 DRAFT Figures 14,
Page 170 and 171: DRAFT Viewed strictly from the infl
Page 172 and 173: DRAFT water removed would fluctuate
Page 174 and 175: DRAFT euryhaline, there were also m
Page 176 and 177: DRAFT 01/90 01/93 01/96 01/99 01/02
Page 178 and 179: DRAFT the intent of that condition
Page 180 and 181: DRAFT included inflows to the model
Page 182 and 183: DRAFT Flows for Sulphur Springs wer
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DRAFT ∆T represents the differenc
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DRAFT Figure 25 Temp (C) 22 Histori
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DRAFT Figure 26 Temp (C) 24 22 Hist
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DRAFT Similar to the coldest period
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DRAFT 5.7. Consideration of future
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DRAFT Culter, J. 1986. Benthic Inve
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DRAFT Shafland, P. L. and K. J. Foo
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APPENDIX A (from Chapter 2) Time se
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Sulphur Springs Water Quality 1991-
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Appendix B. Presence of macroinvert
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Appendix C. Percent composition of
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Appendix C. Percent composition of
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APPENDIX D (from Chapter 3) Percent
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APPENDIX D. Percent composition of
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APPENDIX D. Percent composition of
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APPENDIX E (from Chapter 3) Abundan
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BARE SAND FILAMENTOUS ALGAE COMBINE
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APPENDIX F - HILLSBOROUGH RIVER TEM
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Appendix G Daily values for mean, m
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APPENDIX H (from Chapter 5) Time se
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Experiment Number 6
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Appendix I Daily values for minimum
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28FEB2000 9.8 0.0 1.9 9.7 7.8 . 18.
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12FEB2001 14.0 3.5 1.7 4.6 2.9 1.1
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The Determination of Minimum Flows for Sulphur Springs, Tampa

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