Drought-Proofing Lake Lanier Wilton Rooks
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Drought Management Drought-Proofing Lake Lanier Wilton Rooks kay… In reality it is impossible Lake Lanier since it holds 65 percent of record low of 21 feet below full pool level to isolate Lake Lanier – or any the conservation storage for the entire with disastrous results to the economy Oother reservoir – from the impact Apalachicola-Chattahoochee-Flint River around the lake (Figure 1). of droughts. But is it possible to plan for Basin (ACF) basin but only has 6 percent droughts differently than has been done in of the watershed. The result is that it Endangered species the past? refills much slower than other reservoirs There are mussel and fish species on That is a question that haunts water on the Chattahoochee River making the endangered list in the Apalachicola policy professionals and government management of the lake even more River and Bay whose protection is regulators. In the past, regulators have difficult and unpredictable. the responsibility of the U.S. Fish said that they cannot plan for droughts and Wildlife Service (USFWS). The since they do not trust the forecasts. Factors impacting drought planning USACE has the responsibility to obtain Perhaps that is an indictment of sister for Lake Lanier concurrence from USFWS that their government agencies that focus on In a drought, downstream users from action will not put these species in forecasts, but it does provide a canvas for Metro Atlanta to Apalachicola, Florida jeopardy. Thus, they petitioned USFWS how droughts are viewed. depend on water withdrawals from for their biological opinion regarding Given the view that weather extremes Lake Lanier to meet their needs. Water a minimum required flow of 5,000 are generally predicted to become more conservation policies kick in and ease the cfs (cubic feet per second) into the severe with higher highs and lower lows burden on Lake Lanier, but as experienced Apalachicola River from the confluence (no matter the metric) how do we adjust in 2007, the lake took a major hit. During of the Flint and Chattahoochee Rivers. our thinking and planning for droughts? that experience Lake Lanier reached a The USFWS concurred that as long as What should we expect from our water policy and regulators that will prepare us for potentially worse droughts? Was the drought of 2007-2008 a harbinger of the future for Lake Lanier? Lake Lanier has had a turbulent past for the last 25 years. It has been in the bullseye of legal battles among Georgia, Florida, and Alabama with each state at various times suing each other as well as the US Army Corp of Engineers (USACE). When the US Supreme Court chose not to hear an appeal by Florida on a ruling by the 11th Circuit Court of Appeals that Lake Lanier is authorized as a water supply source, the belief was that the legal battles were over. However, Florida reinvigorated the legal battles with a lawsuit in the U.S. Supreme Court related to Georgia’s use of the waters of the ACF basin thereby depriving Florida of an equitable apportionment of the waters in the Chattahoochee and Flint Rivers. That battle involves Figure 1. Image of Lake Lanier in 2008. Winter 2015 / NALMS • LAKELINE 39 there is a minimum flow of 5,000 cfs at the reduced flow from the Flint required 4 through groundwater – surface water the first gage in the Apalachicola River feet of lake elevation from Lake Lanier to interaction. As water is pumped from the the endangered species would not be put make up the shortfall from the Flint River, aquifer, water from the surface waters into jeopardy, unless an extreme drought illustrating the connectivity of the entire flow into the aquifer, thereby reducing condition existed in which the flow could ACF Basin and the dependence on Lake the flows into the Apalachicola River. drop to 4,500 cfs. Lanier. Agricultural use of the waters of the ACF The USACE has the responsibility The agriculture-rich lands in Basin, including groundwater pumping, to manage the water in the reservoirs on southwest Georgia are dependent on can be almost 50 percent of the average the Chattahoochee River. Under normal irrigation from the Flint River and the annual consumption in the entire basin conditions flows into the Apalachicola Floridan Aquifer, which are connected (Figure 2). River average 20,000 cfs and an important criteria is balancing the conservation storage in the reservoirs. However, during a drought, the conservation storage in the reservoirs downstream of Lake Lanier are rapidly depleted leaving Lanier as the only available resource to meet the minimum required flows. This results in a condition where thousands of cubic feet per second are discharged from Lake Lanier just to meet the minimum required flow of 5,000 cfs into the Apalachicola River. During the drought of 2007-2008, discharges from Lanier in November 2007 averaged 2,244 cfs with a high of over 4,000 cfs. Imagine the view of the Chattahoochee River being out of its banks as it flowed past Atlanta while Lake Lanier was experiencing its worst drawdown in history. Metro Atlanta residents were under strict water consumption policies that created a contradictory situation that was only explained by the role of Lake Lanier in the total ACF Basin. Why is the Flint River important to Lake Lanier? A compounding factor is the role of the Flint River in the ACF Basin. The Flint, which starts under the runway at Hartsfield-Jackson Airport in Atlanta, flows through middle Georgia and the agriculture southwest Georgia, draining 8,460 square miles of the 19,600 square miles of the total ACF Basin. Under normal rainfall conditions it contributes approximately 45 percent of the total flow into the Apalachicola River. However, during the 2007-2008 drought, the flow from the Flint into the Apalachicola River reached a low as 600 cfs during the month of November 2007 with an average of less than 1,100 cfs for that month. The discharges from Lanier had to make up the difference to reach the 5,000 cfs minimum required flow. During the drought, one calculation estimated that Figure 2. Image of ACF Basin showing Flint River. 40 Winter 2015 / NALMS • LAKELINE So what are the elements of dropped consistently since 2000 and with limited shoreline impacts. drought planning? total consumption has dropped even Some investments would Forecasting though the population has increased. have to be made if 1073 msl Drought planning has to start with These savings resulted from emphasis were to replace 1071 as the forecasting. Unfortunately the weather on water efficiency plans and tiered “ceiling” used by the USACE crystal ball gets murky the further out one water consumption rates that provide for management of the lake tries to project. Major weather factors like incentives to residents and businesses level. But those investments strong El Nino or La Nina patterns can to upgrade fixtures and reduce are minimal compared to new give useful information but even those consumption. During a drought, reservoir construction. can be subject to countervailing forces. further actions are imposed to reduce § Currently there is 14 feet of Based on recent trends and projections, consumption even more, but with the flood control (1085-1071 msl) expectations are for shorter periods Metro Atlanta population increasing in Lake Lanier that is used of heavier rains and longer periods of substantially, even more per capita by the USACE to manage droughts. Predicting a precise temperature restrictions will have to be imposed. potential flooding situations. range or rainfall is only valid for a few 2. Increase storage – It is generally The USACE argues that this days out. However forecasting related understood that additional storage amount is needed in order to major events such as a wetter or of water would be beneficial during to provide adequate flood colder season than normal do provide a drought. There are political and protection in the event of useful information for drought planning. environmental arguments for and severe rainfall events either Predicting when a drought will start is against this but the benefit during a above or below Lake Lanier. difficult but predicting when it will end is drought is difficult to deny. There Over the 50 year life of Lake equally critical for planning purposes. are few options in the ACF Basin Lanier, only 6 feet has been to increase storage. A reservoir on required for this purpose. Contingency Planning the Flint River was taken off the § The USACE does not have If a drought is expected, what actions table in the 1960s and there are the authority to raise the can water managers and government scant possibilities that it will be full pool level without U.S. regulators take to mitigate the impact? resurrected. Once past the geological Congress authorization. With The goal of any planning should be to fall line there are limited possibilities the associated political issues extend the usefulness of available water for additional reservoirs of significant that exist among the three as long as possible. That means curtailing volume. states, this is considered a low usage to the maximum degree possible. In the Metro Atlanta area, probability. Since Lake Lanier holds 65 percent of various investigations are underway the water storage for the entire ACF for additional reservoirs. However, Role of the ACF stakeholders (ACFS) basin, extending the useful life of the a major source of additional storage Six years ago, a group of water stored water is extremely important. In is to increase the full pool “ceiling” professionals, environmentalists, and addition to Metro Atlanta water users, used by the USACE for Lake Lanier consumers organized to develop a solution numerous downstream users depend on it by 2 feet from 1071 above mean sea to the 20-year legal battle among the three to maintain reservoirs, provide drinking level (msl) to 1073.