Chapter 1 Minimum Flows and Levels - Southwest Florida Water ...

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EXECUTIVE SUMMARY This is a summary of the Scientific Peer Review Panel’s (“Panel”) evaluation of the scientific and technical data, assumptions, and methodologies used by the Southwest Florida Water Management District (District) in the development of proposed minimum flows and levels (MFLs) for the upper Braden River, from Linger Lodge to Lorraine Road. The approach used in setting MFLs for the upper Braden River follows the established protocols that have been effectively used by the District in the past. The Panel continues to endorse the District’s overall approach for setting MFLs in riverine ecosystems and finds particularly merit in the use of seasonal building blocks, multiple benchmark periods based on multi-decadal climate variability, the use of multiple analysis tools for protecting both low and high-flow regimes, and the expression of MFLs as percent flow reductions. The application of this approach for the upper Braden River is thorough and defensible. The methodology is sound, the data are appropriate for the task, and the findings are based on best available science. The assumptions, that are inherent in the scientific approaches that are employed, are well documented and represent current understanding of how best to protect healthy aquatic ecosystems. The derived MFLs are reasonable and likely to sustain the ecological health of the Upper Braden River. Overall, the Panel finds the methodologies used are appropriate, even innovative. The District has added two new techniques for data acquisition and presentation (the Light Detection and Ranging (LiDAR) method to collect transect data for the HEC-RAS models and statistical medians to present historical flow data). District staff members have clearly spent a great deal of time and effort trying to arrive at a scientifically reasonable set of recommendations and have largely succeeded. The authors are to be commended for addressing one of the most difficult issues when carrying out these types of studies, trying to interpret exactly the intention of the legislators when they drafted the legislation. The discussion, relating a good instream flow standard in the context of the legislation to prevent significant harm, is well thought out and articulate. However, the Panel continues to believe that the adequacy of the low-flow threshold and the use of a de facto significant-harm criterion, based on a 15% reduction in habitat availability, has not been rigorously demonstrated and will remain presumptive until such time as the District commits to the monitoring and assessment necessary to determine whether these criteria are truly protective of the resource. We are concerned that the District, to date, has taken no visible 8-2
steps to reduce the uncertainty and subjectivity associated with these criteria and urge them to move forward quickly to develop and implement an adaptive management framework that that will facilitate such assessments. INTRODUCTION The Southwest Florida Water Management District (SWFWMD) under Florida statutes provides for peer review of methodologies and studies that address the management of water resources within the jurisdiction of the District. The SWFWMD has been directed to establish minimum flows and levels (designated as MFLs) for priority water bodies within its boundaries. This directive is by virtue of SWFWMD’s obligation to permit consumptive use of water and a legislative mandate to protect water resources from significant harm. According to the Water Resources Act of 1972, minimum flows are defined as “the minimum flow for a given watercourse shall be the limit at which further withdrawals would be significantly harmful to the water resources or ecology of the area” (Section 373.042 F.S.). A minimum level is defined as “the level of groundwater in an aquifer and the level of surface water at which further withdrawals would be significantly harmful to the water resources of the area.” Statutes provide that MFLs shall be calculated using the best available information. The process of analyzing minimum flows and levels for the upper segment of the Braden River is built upon the analyses previously performed on the upper Peace River (SWFWMD 2002), peer reviewed by Gore et al. (2002), the middle Peace River (SWFWMD, 2005a), peer reviewed by Shaw et al. (2005), the Alafia and Myakka Rivers (SWFWMD, 2005b, c), peer reviewed by Cichra et al. (2005), and the upper Hillsborough River (SWFWMD 2007), peer reviewed by Cichra et al. (2007). The upper Braden River MFL methodologies incorporate many of the recommendations of these earlier peer reviews, as well as key improvements developed by District staff. Establishment of minimum flows and levels generally is designed to define thresholds at which further withdrawals would produce significant harm to existing water resources and ecological conditions, if these thresholds were exceeded in the future. This review follows the organization of the Charge to the Peer Review Panel and the structure of the draft report. It is the job of the Peer Review Panel to assess the strengths and weaknesses of the overall approach, its conclusions, and recommendations. This review is provided to the District with our encouragement to continue to enhance the scientific basis that is firmly established for the decision-making process by the SWFWMD. Extensive editorial comments and errata for the upper Braden River MFL draft report are provided as an Appendix. 8-3
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Proposed Minimum Flows and Levels f
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Table of Contents TABLE OF CONTENTS
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5.5 PRESCRIBED FLOW REDUCTION FOR B
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Figure 2-19. Potassium concentratio
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Figure 5-13. Median daily flow at t
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mean feature elevations are listed
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For the high flow season of the yea
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Acknowledgements The authors would
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fluctuations in water flows or leve
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Common to this list and the flow re
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Fundamental to the approach used fo
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300 250 Block 1 Block 3 Block 2 Flo
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are outlined in Chapter 4. In Chapt
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as the freshwater segment upstream
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attributed to analytic precision di
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Figure 2-4. 1999 land use/cover map
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Table 2-2. Land use/cover and land
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Figure 2-8. 1999 Land use/cover map
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Figure 2-10. 1972 Land use/cover ma
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Smith and Stopp (1978) note that "i
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2.4.2.1 Multidecadal Periods of Hig
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2.4.3.2 Step Trend in River Flows K
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Table 2-4. Results of Kendall's tau
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2.4.4 Benchmark Periods Climate-bas
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Oscillation were examined. On a sea
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Water Chemistry 2.4.6 Water Quality
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Braden River near Lorraine, FL 0.6
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Peace River at Arcadia, FL 10 Potas
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Table 2-8. Summary statistics for B
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3.2 Resources and Area of Concern T
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habitat, the greater area of stream
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levels such as fish have been shown
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Figure 3-1. Example of low flow in
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USGS Braden River near Lorraine gag
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instream cross-sections were sample
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Figure 4-2. Upstream vegetation cro
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supports water surface profile calc
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The HEC-RAS model was run using 21
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Adult Spotted Sunfish Adults - Brad
Page 79 and 80: species of interest. For example cu
Page 81 and 82: 4.4 Seasonal Flow and Development o
Page 83 and 84: Wetted Perimeter - Sta. 44.9 25 20
Page 85 and 86: factors, the most conservative of w
Page 87 and 88: Chapter 5 Results and Recommended M
Page 89 and 90: Wetted Perimeter Requirements Flow
Page 91 and 92: 40 35 30 25 20 15 10 5 0 May June M
Page 93 and 94: Floodplain profiles and vegetation
Page 95 and 96: mean elevation of the Oak/popash ve
Page 97 and 98: Table 5-3. Mean (±SD) flows at the
Page 99 and 100: Elevaton (NGVD) 27.0 22.0 17.0 12.0
Page 101 and 102: Table 5-7. Median elevations, in fe
Page 103 and 104: 80 70 60 Flow reduction (%) 50 40 3
Page 105 and 106: Table 5-8. Recommended percent flow
Page 107 and 108: 100 90 80 % DOMINANCE 70 60 50 40 3
Page 109 and 110: Table 5-9. Mean elevation of instre
Page 111 and 112: The second standard was developed t
Page 113 and 114: Table 5-10. Proposed Minimum Flows
Page 115 and 116: Division Information and Technology
Page 117 and 118: Hupalo, R., C. Neubauer, L. Keenan,
Page 119 and 120: communities in the corridors of the
Page 121 and 122: Wharton, C.H., W.M. Kitchens, E.C.
Page 123 and 124: Confined Aquifer - A term used to d
Page 125 and 126: Instream Habitats - A specific type
Page 127 and 128: Riffle - A relatively shallow reach
Page 129: Chapter 8 Appendix A A Review of
Page 133 and 134: 2007). In addition, the approach us
Page 135 and 136: with limited biological knowledge o
Page 137 and 138: the other factors listed above or w
Page 139 and 140: have now been developed and adopted
Page 141 and 142: An example of the primary output fr
Page 143 and 144: prevent negative effects associated
Page 145 and 146: methods, such as LiDAR, to improve
Page 147 and 148: habitat reduction criterion and the
Page 149 and 150: Summary, Special Publication SJ2002
Page 151 and 152: Errata / comments by page number in
Page 153 and 154: 4-20 Section 4.7.1, 1 st paragraph,
Page 155 and 156: Chapter 9 Appendix B - Staff Respon
Page 157 and 158: 2) The panel notes that the period
Page 159 and 160: 4) One aspect of Chapter 2 should b
Page 161 and 162: Preventing Significant Harm - 15% C
Page 163 and 164: they aren't getting enough particul
Page 165 and 166: Habitat Criteria and Characterizati
Page 167 and 168: Compliance Standards and Proposed M
Page 169 and 170: Glossary of Terms 13) When an inter
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