In October 2013 we announced an initiative to assess our flood storage capacity to test the possibility of reducing our current flood storage allotment. More specifically, the study will provide information that will better define the present need for flood storage in the basin. In the announcement we estimated the study would take approximately 12 months. Based on recent updates from the Hydrologic Engineering Center (HEC), the organization conducting most of the study, the results will be delayed about six more months.

To recap, the assessment will look at two things:

1) the ability of the projects to contain the Probable Maximum Flood (PMF), which however unlikely, is the greatest rain event the basin could ever expect; and

2) the ability of the projects to contain a number of smaller and more likely periods of rainfall intensity, from 10- to 500-year rain events. The assessment models intense rain events, and how runoff occurs in the basin with the present level of development. It will compare impacts of each of these rain events using our current 4-foot drawdown with impacts of lesser amounts of flood storage (smaller winter draw downs). The idea is to assess how much flood storage we need and identify what kind of risk we are taking if we reduce the winter drawdown and then get the inevitable large spring rain. If the study indicates that all the present flood storage is not needed, additional studies could be performed to determine how much storage is economically justified.

Update on the Savannah River Basin Comp Study (Interim 2)

In February we provided an update on the progress of the Comp Study. We estimated then, that the draft report would be ready for review in about 12 months (putting us at approximately February 2015). An updated estimate on completion of a draft report for public comments is about January 2016.

After we ran an initial data set through the models, the Corps and the study sponsors agreed that we needed to add data from 2013 to our inflow dataset to have more accurate results.  We are obtaining that information to make sure we capture the recovery of the system from the most recent drought, possibly the new drought of record, which occurred from 2011 to 2013. Georgia Environmental Protection Division (GAEPD) is now collecting the needed data and when their work is complete, we will run the reservoir simulation models again to evaluate each of the six proposed alternatives.

Other work continues. The Nature Conservancy (TNC) has been performing research and held a workshop to help define parameters for Alternative 3: “Release Based on Environmental Flow Restriction.” TNC is finalizing their report from that workshop and they will then update the ecosystem functions model to incorporate additional environmental criteria that we will use to evaluate each alternative.

To recap, the purpose of this interim is to answer the following questions:

1) How low can we reduce daily outflows at the Thurmond Dam during drought conditions?

2.) How long can we sustain these minimum outflows before significant negative impacts would occur to the downstream economy and environment?

This portion of the study will examine value, risks and impacts of six alternative operating protocols for the current Drought Contingency Plan. You can see summaries of these alternatives here.

~Russell Wicke, Corporate Communications Office Chief

– See more at: http://balancingthebasin.armylive.dodlive.mil/2014/11/19/compstudy/#more-1805

Representatives from the U.S. Army Corps of Engineers (USACE), Southeastern Power Administration (SEPA), and Duke Energy signed a new operating agreement in Elberton, Georgia, Oct. 17 defining how water resources will be shared among the Duke Energy and Corps reservoirs in the Savannah River Basin. This operating agreement will increase drought tolerance within the watershed and promote conservation efforts.

The agreement encompasses the reservoirs in Duke Energy’s Keowee-Toxaway Project (Lakes Jocassee and Keowee) and Bad Creek Reservoir, and the Corps’ reservoirs (Lakes Hartwell, Russell and Thurmond).

“We believe this new agreement represents a balanced approach to managing our respective hydroelectric reservoirs in the Upper Savannah River Basin during droughts,” explained Steve Jester, Duke Energy’s vice president of water strategy, hydro relicensing and lake services. “We worked very closely with the U.S. Army Corps of Engineers and the Southeastern Power Administration to develop the agreement and look forward to continuing the partnership.”

“Good stewardship of the basin’s freshwater resource is one of our highest priorities, and this agreement advances that effort,” said Stan Simpson, Savannah District’s senior water manager. “We are committed partners with SEPA and Duke. We are proud to work with them to provide innovative solutions to operational needs as well as basin needs.”

The new operating agreement supersedes a 1968 agreement put in place to ensure proportionate use of water resources during drought at both the Corps’ reservoirs and Duke Energy’s reservoirs. Since 1968 there have been many changes in both the Corps and Duke Energy systems without modification to the operating agreement. For example, the Corps and Duke Energy have each constructed an additional reservoir since 1968 in the Savannah River Basin. Both reservoirs incorporate pumped storage capabilities that affect operation of their systems. The Corps constructed the Richard B. Russell Pumped Storage Project; Duke Energy constructed the Bad Creek Pumped Storage Project and the Oconee Nuclear Station. The Corps also modified its reservoir operations through implementation of a drought contingency plan, with the latest update occurring in July 2012.

While the new agreement still balances the percent of remaining usable water resources between Duke Energy and Corps reservoirs, it also incorporates Duke Energy’s drought tolerance measures (Low Inflow Protocol) to coordinate drought mitigation measures in the upper basin. This results in a more resilient operation, more prudent water conservation and accounts for the new pumped storage facilities in the basin. The new agreement is consistent with the Keowee-Toxaway Relicensing Agreement, and it allows Duke Energy to make flow releases to support downstream water needs deeper into severe droughts than the 1968 agreement.

The new agreement incorporates the Corps’ 2012 Drought Plan so that minimum outflows from Thurmond Dam will remain the same. The agreement was also designed to be environmentally friendly. An Environmental Assessment demonstrates the new Operating Agreement would result in no significant environmental impacts and represents sound natural resource management practices and environmental standards.

~By Russell Wicke, Corporate Communications Chief

– See more at: http://balancingthebasin.armylive.dodlive.mil/2014/10/20/newoperatingagreement/#more-1756

The final observed rainfall totals for September ranked above average at Thurmond and Russell sub basins, and below average at Hartwell sub basin.

Throughout September, the National Weather Service recorded rainfall on 24 days at Thurmond, 23 days at Hartwell, and 17 days at Russell.

Thurmond sub basin received 114.6 percent of normal rainfall totaling 4 inches, a half inch above the September average of 3.5 inches.

Russell sub basin received 104.9 percent of normal rainfall totaling 3.9 total inches, 0.2 inches above its September average of 3.7 inches.

Hartwell sub basin received 78.6 percent of normal rainfall totaling 3.7 total inches of rainfall, about 1 inch short the September average of 4.7 inches.

During September, observed rainfall totals at Thurmond and Russell sub basins were 1.1 and 0.5 inches, respectively, above August observed rainfall totals. Hartwell sub basin received 0.6 inches less than August observed rainfall totals.

Hartwell and Russell sub basins had the largest rain events on Sept. 8, with 1.3 and 1.2 inches of rain, respectively. Although Thurmond sub basin received the highest total observed rainfall, its single-day peak was 0.7 inches on Sept. 13.

~ Chelsea Smith, Public Affairs Specialist