Review of the St. Johns River Water Supply Impact Study Report 1 (2009) / Chapter Skim
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2 St. Johns River Water Supply Impact Study: Cross-Cutting Issues
2 St. Johns River Water Supply Impact Study: Cross-Cutting Issues
Pages 18-26
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From page 18... ...
Johns River Water Management District (SJRWMD or "the District") has undertaken a large and complicated study to evaluate potential environmental impacts of additional consumptive-use water withdrawals from the St.
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From page 19... ...
Nonetheless, the committee recognizes the need for comparable impact analyses on the Ocklawaha River, particularly its lower reaches, which are the most likely to be affected by additional water withdrawals in the basin. In addition, the committee concludes that to avoid future misunderstandings the SJRWMD should provide a better explanation of the basis for its decisions on this issue in public documents, presentations, and web-based materials related to the WSIS and should make the focus of the WSIS on the main stem St.
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From page 20... ...
The danger in such an approach, however, is that the study could become seven separate studies each with narrowly focused conclusions in the subject expertise of the workgroup rather than an integrated assessment in which output from one workgroup serves as input to another group for an iterative analysis of ecosystem impacts. For example, changes in the benthic macroinvertebrate assemblage may engender changes in the fish assemblage, which in turn may stimulate changes in other segments of the biological community, and feedbacks also occur, making crossworkgroup collaborations essential to a comprehensive analysis.
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From page 21... ...
Furthermore, simple adaptation of the Everglades framework is discouraged. However, a more modest conceptual framework might be represented as either a matrix or flow chart that links possible physical effects caused by surface water withdrawal to the perceived chain of ecological effects and their consequences and the resulting research needs.
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From page 22... ...
Johns reduced water levels surface water increased withdrawal downstream flow upstream movement of salt water boundary increased increased reversing groundwater (tidal) flows discharge FIGURE 2-1: Sketch of hypothesized chain of physical consequences caused by surface water withdrawals.
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From page 23... ...
These issues should become part of the conceptual framework created during Phase II of the WSIS. Investigating Individual Species as Indicators of Community Change Different workgroups of the WSIS are analyzing potential impacts of additional water withdrawals on several major types of biota: submerged aquatic vegetation (SAV)
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From page 24... ...
Water withdrawal could also alter the mosaic of environment types in both estuarine and freshwater segments of the basin -- changes that could substantially affect resident species and migratory fishes and birds that use mosaic environments to survive throughout the year. WATER AND NUTRIENT BUDGETS In reviewing Phase I of the WSIS, the committee often had difficulties placing the proposed water withdrawals into context relative to current conditions in the river.
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From page 25... ...
Nutrient budget information also is needed to evaluate the importance of nutrient loadings from the return flows discussed below. The extent to which extended periods of low flow conditions will exacerbate algal bloom conditions in Lake George and other large impoundments of the river cannot be assessed properly without more comprehensive nutrient budget information for the system as a whole.
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From page 26... ...
SUMMARY In summary, several issues touch on the goals of many of the workgroups and should be considered by each as the WSIS enters its second phase. These include the need for integration of information and results across the workgroups, assessment of future growth in the basin and its relationship to potential withdrawals, creation of water and nutrient budgets for the basin, and more comprehensive investigation of how the floodplains and wetlands in the basin will be dewatered by potential water withdrawals.
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