Corps releases draft changes to drought plan
Officials seek public comments
The Hartwell Sun, June 22, 2017
Officials from the Corps of Engineers’ Savannah District released a draft report containing recommendations to improve management of waterresourcesintheSavannah River during drought.
Government agencies, industry, civic groups and individuals may submit comments through noon Eastern Time July 13, 2017.
The study put together detailed information to determine “the amount of flow required during severe and prolonged drought.” Officials seek comments on the study and updated drought plan before determining the final course of action.
The public can review the entire draft study and draft drought plan online at http:// ow.ly/rUyF30cA7Tv
The Corps, along with its study partners, the Georgia Department of Natural Resources, the South Carolina Department of Natural Resources and The Nature Conservancy, examined six different alternatives to manage water during drought, comparing each to keeping the current plan. The recommended alternative, labeled “Alternative 2” achieves the most positive impacts and the least negative impacts to the water resources compared to each of the others.
Under the recommended alternative, drought trigger level 3 rises 6 feet bringing the most restrictive outflows into play much earlier in drought. In addition trigger level 1 would remain con- stant year-round as opposed to dipping in relation to the winter drawdown. This has
the effect of possibly reduc- ing outflows sooner than the current plan.
Alternative 2 also keeps level 2 flat year-round reducing flows further, sooner than in the current plan.
The release of the draft report marks the second interim of the Savannah River Basin Comprehensive Study, which started in 2012. This study includes an environmental assessment of the alternatives. The recommended plan would update the Savannah District’s Drought Contingency Plan. The drought plan directs water managers and others on how to use and conserve resources when drought strikes the region.
The alternative recommended for adoption makes some significant changes to water management during drought.
“Of the six new alternatives studied, the group recommended one with the greatest benefit to the greatest number of purposes assigned to the three Savannah District reservoirs,” Nathan Dayan, the study’s Environmental Team Lead, said. “We examined impacts to the environment, economics, recreation, hydropower, water supply and water quality, and down- stream navigation.”
“Both states worked alongside The Nature Conservancy and the Corps of Engineers to make this a true partnership in adding to our knowledge of the Savannah River Basin and in updating the drought contingency plan,” Dayan said.
The Savannah River Basin Comprehensive Study (SRBCS) Interim 2 evaluate potential changes to the U.S. Army Corps of Engineers (USACE) Drought Contingency Plan (DCP) for the Savannah River Basin. The Georgia Department of Natural Resources (GADNR), the South Carolina De- partment of Natural Resources (SCDNR), and The Nature Conservancy (TNC) were the non-Federal sponsors for the study. The Project Delivery Team (PDT) was comprised of selected staff from the GADNR, SCDNR, TNC, and USACE. SRBCS Interim 2 recommends a Drought Contingency Plan (DCP) that would improve management of water resources for all authorized project purposes during prolonged low inflows. Those improvements result from operational changes that impact the timing and magnitude of releases from J. Strom Thurmond (JST) Dam and Reservoir during droughts. Physical modifications to the existing projects or new construc- tion features for the projects were outside of the scope of Interim 2.
The SRBCS Interim 2 formulated, evaluated, and compared a wide array of drought manage- ment alternatives. Each alternative includes various elevation triggers and required releases from the JST Dam and Reservoir.
The PDT examined the No Action Alternative (NAA) and six action alternatives through the use of engineering computer model simulations, economic analysis, and an environmental assessment. They evaluated the potential effects of each alternative on all project purposes, both in the reservoirs and downstream of the reservoirs.
The team compared the final array of alternatives for their effects on hydropower and recreation using economic factors. They used noneconomic factors for the other project purposes: environmental stewardship, navigation, water supply, and flood risk management. The PDT selected percent change as the method to give each project purpose comparable units of measure.
Alternative 2 produces the most positive impacts and least negative impacts on the authorized project purposes. Therefore, Alternative 2 is the Tentatively Selected Plan.
The Plan would increase conservation opportunities within the reservoirs by flattening the level 1 and 2 triggers, raising trigger level 3, and slightly decreasing the required discharge for each trig- ger level. Drought trigger level 1 would be located at the same elevation as the current winter guide curve of 4 feet down from the summer guide curve.
The guide curve is USACE’s operational target for the reservoir elevation. Drought trigger level 2 would be located 2 feet below drought trigger level 1. Drought trigger level 3 would be located 2 feet below drought trigger level 2, which is 6 feet higher than in the NAA. When in drought trigger level 1, JST would target a daily average release of 4,000 cfs. During level 2, discharges would be 3,800 cfs from February through October, and 3,600 cfs from November through January. During level 3, discharges would be 3,600 cfs from February through October, and 3,100 cfs from Novem- ber through January.