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Re-Engineering Water Storage in the Everglades: Risks and Opportunities
Given the above comments and the possibility that other storage options (e.g., ASR) may not provide the amounts of water needed to fulfill the restoration plan, the committee judges that it would be prudent to revisit the question of whether Lake Okeechobee can provide some of the sought-for water storage. A wide range of options exist. Some of them, including options explored early in the Restudy, would have extreme effects on lake levels and would diminish the value of the lake as an ecological resource and probably as a sport fishery. These options likely would be opposed by a wide range of stakeholder groups, including the sport-fishing community and environmentalists. The lake is widely considered to be a valuable aquatic resource, even in its somewhat degraded condition, and proposals that would relegate the lake primarily to use as a water-storage device are likely to be controversial. For this reason especially, any reconsideration of Lake Okeechobee’s role in storage would need to include careful consideration of socioeconomic and ecological factors, including short- and long-term financial costs.
One of the more extreme options involved splitting the lake into two sections with a large dike. One section would include the littoral zones on the west side of the lake, in which water levels would be maintained within a range that would promote a healthy littoral plant community. The other section would include most of the open water portions of the lake on the east side, and water levels would be allowed to fluctuate to rather extreme highs and lows. A second option considered in early Restudy modeling runs allowed the entire lake to be used for water storage, and although the runs demonstrated that maximal use of storage in Lake Okeechobee would be “cost effective and hydrologically efficient” (USACE and SFWMD, 1999), they produced extreme fluctuations in lake levels, which likely would adversely affect the lake ecosystem. More modest fluctuations in water levels, including relatively small increases in maximum lake stage, apparently were not explored in these runs.
Smaller fluctuations and smaller increases in maximum stage of Lake Okeechobee obviously would not provide the total amount of storage that the unaltered system of the nineteenth century had and that may be required to offset the loss of another major storage component, such as ASR, should it prove infeasible. Nonetheless, moderate changes in lake stage could contribute substantially to system storage. As noted previously, an increase in maximum lake stage of only 0.5 ft would provide a water storage volume nearly equal to that of the two reservoirs (total of 22,500 acres plus an additional 7,500 acres devoted to STAs) proposed to be constructed north of Lake Okeechobee (see Chapter 2). Such changes may have only small negative effects on lake quality in the long term, especially once the problem of excessive nutrient loading to the lake is finally solved, and it may even lead to positive changes, such as a larger open-water habitat and a more accessible littoral zone on the southwest side of the lake. Thus, there is the potential to provide ecological benefits earlier in the process. Other storage options, including the proposed storage reservoirs north of Lake Okeechobee, have their own environmental costs. Any such changes should be undertaken using adaptive management to maximize learning opportunities.