May 8, 2012

The Savannah District Water Managers are excited about the drought plan update.

The main element proposed in the current Draft Environmental Assessment (EA) is to determine our water releases from the three-reservoir system during drought based on inflow and pool elevation. The current drought management strategy uses pool elevation as the only drought criteria that designates how much the Corps should release from the reservoirs.

While it's easy to understand the pool elevation trigger, it does not get initiated until the pools have already fallen to specified trigger levels. We are going to be using the 28-day average flow at the U.S. Geological Survey (USGS) gage on the Broad River at Bell, Ga., as the index site for the inflow-based trigger. The Broad River is an unregulated drainage basin with 1,430 square miles above the gage site.

The Broad River ultimately flows into the Thurmond reservoir downstream of Richard B. Russell Dam. The current drought plan does not require a flow reduction until the pools have fallen to the next drought trigger level.

In the past, the Corps has tended to transition to the next lower drought state as forecasts changed. In the future, inflows will help us make that decision.

Here's how we—the water managers—see the EA working:

Every Wednesday, as we prepare the water release declaration, the average flow at the Broad River gage for the previous 28 days will be compared to the 28-day average flow, at that same gage, for that same day of the year, for the previous 50+ years of record.

When the current 28-day average is less than the 10 percent of all the years, we would transition flows to the next lower drought level flow. The USGS uses 10 percent as the breaking point between dry and drought. More information on the concept can be found on the USGS Water Watch website.

Here's a simplified breakdown of our current Drought Contingency Plan compared to the proposed EA update:

• Level 1 Trigger – Thurmond elevation reaches 326 ft-msl – Outflows reduced to 4,200 cfs max
• Level 2 Trigger – Thurmond elevation reaches 324 ft-msl – Outflows reduced to 4,000 cfs max
• Level 3 Trigger – Thurmond elevation reaches 316 ft-msl – Outflows reduced to 3,800 cfs max

• Level 1 – Outflows reduced from 4,200 cfs to 4,000 cfs
• Level 2 – Outflows reduced from 4,000 cfs to 3,800 cfs
• Level 3 – Outflows reduced from 3,800 cfs to 3,600 cfs

While all of these features will help conserve water, they will not end a drought. However, the plan would help store additional water in the reservoirs earlier in drought.

For daily updates on water management in the Savannah River Basin, visit our water management webpage. To learn more about the multiple users of the Savannah River, watch the Corps' 8-minute video clip "Balancing the Basin."

The Corps of Engineers coordinates water management efforts with federal and state natural resource agencies to balance the needs of the Savannah River’s upstream and downstream users. The Savannah District’s water management plan and drought plan were coordinated with input from these agencies, and we continue to consult them in our daily operations. Our water managers constantly monitor and adjust outflows from the three reservoirs to balance various needs. We often receive questions about our management of the reservoirs and want to share the answers with you in our recently-updated Frequently Asked Questions

From Balancing the Basin, February 10, 2012

The U.S. Army Corps of Engineers releases water from the Hartwell, Richard B. Russell and J. Strom Thurmond reservoir system to meet upstream and downstream needs – drinking water, industrial uses, utilities, and environmental and natural resource protection. These needs continue year round. Many thousands of people, dozens of industries, and some major utilities depend on a constant supply of water from the reservoirs. By law, downstream environmental needs must also be met. As a water resource management agency, the Corps seeks to balance upstream and downstream needs within the authorized purposes of the reservoirs.

The Savannah District is addressing potential minor adjustments to the drought contingency plan through an Environmental Assessment, and potential large-scale modifications to the entire three-project system through the Savannah River Basin Comprehensive Study. Below are some updates on these topics:

• The Corps began work in November 2011 on an “Interim Drought Plan Environmental Assessment” (EA) that will help evaluate minor adjustments to the 2006 Drought Contingency Plan that could allow the Corps to implement changes during the current drought, depending on the recommended alternative and project conditions.
• The draft EA is scheduled to be released for agency review and public comment in April 2012. The public comment period would last 30 days.
• The drought operation rules from the chosen alternative within the EA would be in effect until the EA is superseded by subsequent evaluations, such as the Savannah River Basin Comprehensive Study.

• The Savannah River Basin Comprehensive Study will examine the extensive interactions of resources, project purposes, and environmental and social aspects of the entire basin. This study is needed to assess and recommend changes to the water management plan that are outside of the Corps’ existing Congressionally-defined authorities. Once fully complete, it will provide data and recommendations for extensive changes in water management and water resource allocations for the entire basin. The study represents a joint endeavor between the Corps and the states of Georgia and South Carolina. Funding is cost-shared between the federal government and the states (non-federal sponsors).
• The first portion of the study was completed in 2006 at a cost of $1.8 million. This portion included a water supply survey, a flow dataset, and a computer model for the Savannah River Basin to identify how changes in operations affect reservoir levels and downstream conditions. This portion also included the 2006 EA that updated the Corps’ 1989 Drought Contingency Plan for the Savannah River Basin in response to the drought of record from 1998-2002. This portion of the Comprehensive Study was crucial in updating the drought plan and reducing outflows earlier in drought at levels 1 and 2 — keeping more water in the reservoirs while still meeting downstream needs.
• The next portion of the Comprehensive Study will focus on updates to the Drought Contingency Plan using data gathered during the last drought of record (2007-2009). It will not result in wide-sweeping changes to pool allocations or outflows; it will only consider improvements and refinements of drought operations. Results of this portion of the study would guide long-term changes to the Corps' Drought Contingency Plan.
• The Corps continues to work closely with officials from Georgia and South Carolina to resume the Comprehensive Study. The states identified their desire for a more extensive update on the Drought Contingency Plan as their top priority.
• The Corps is working with the Georgia Department of Natural Resources (GADNR) and the South Carolina Department of Natural Resources (SCDNR), to develop the scope for the next portion of the Comprehensive Study and obtain the necessary funding to move forward. In addition, The Nature Conservancy has volunteered to help with the Comprehensive Study. Details of The Nature Conservancy's potential involvement have not been finalized. The cost for this portion of the study is estimated at $1 million, shared 50-50 by the federal government and non-federal sponsors,
• Recently, officials from South Carolina indicated that additional funds for that state’s share of the study may be added to their budget, so they may receive funding to resume work on the study. Georgia has indicated that it stands ready to provide in-kind services for their portion of the study. The federal portion of the funds to pay for the extensive update on the Drought Contingency Plan is available and ready to use.
• Currently, executing this portion of the Comprehensive Study is a high priority in the Savannah District’s civil works program. The Corps is working hard to reach resolution with all parties involved who share the precious natural resources of the Savannah River Basin.

From Balancing the Basin, October 25, 2011

The Savannah District invited three federal natural resource agencies to share information with our stakeholders about their roles in the management of the Savannah River Basin.

Message from U.S. Fish and Wildlife Service (USFWS)

Message from National Oceanic & Atmospheric Administration (NOAA)

Message from Environmental Protection Agency (EPA)

From Balancing the Basin, May 11, 2011

Improved water quality means better fishing – especially in the tailwaters just below Hartwell Dam. With a modification to its turbines inside the dam, the Corps of Engineers turned the area just below the dam into a trout haven.

Like many southeastern reservoirs, Hartwell Lake has three distinct water layers that differ in temperature and chemistry. By late summer the "hypolimnion layer," the cool bottom area of water in the reservoir, typically has low dissolved oxygen (DO). Since the water released through the dam for hydropower comes from this layer, the low oxygen content has a negative impact on the tailwater as it leaves the dam and enters Lake Russell. While trout prefer the colder water, the low oxygen content made it difficult for them to thrive. A modification to the turbines changed all that.

The Hartwell tailwater has always been of particular concern because of its status as a “put and take” rainbow trout fishery. When the Corps modified its turbines inside the Hartwell Dam, the area just below the dam became an excellent location for South Carolina and Georgia to increase their stocking of rainbow trout.

Recognizing an opportunity to improve fisheries habitat in the Hartwell tailwater through improving the quality of water released during hydropower generation, the Corps contacted the Tennessee Valley Authority (TVA) in 1997 to assist in identifying possible water quality improvements at the Hartwell Dam and power plant. After an on-site engineering study, the Corps followed TVA’s recommendations to install turbine hub baffles and 10-inch air supply pipes to four of the five generating units. These modifications, referred to as "turbine venting," allow air to diffuse into the water as it flows past the turbines during generation. This results in a much-needed increase in dissolved oxygen levels in the tailwater.

Water quality information collected since installation of the hub baffles indicates that DO concentrations are being improved by at least 2 mg/l during the period when oxygen concentrations are low. As a result of these improvements, South Carolina Department of Natural Resources (SCDNR) and Georgia Department of Natural Resources (GADNR) expanded their stocking season and increased the number of trout stocked in the Hartwell tailwater.

"Stocking later than June was not an option in the past," said Dan Rankin, SCDNR Regional fisheries Coordinator, “With the improvements from turbine venting, we are now able to stock trout as late as August and we have plans to stock right through the fall months.” In fact, Georgia and South Carolina Departments of Natural Resources now stock approximately 24,000, 9” to 12” rainbow trout annually and provide a viable and unique cold water fishery downstream from the Hartwell Dam.

The location of the Hartwell tailrace fishery makes it unique. Trout waters are located in the mountains, where water temperatures remain cool throughout the summer. The cool hypolimnetic water released during power generation makes a trout fishery possible in the piedmont. The same water once extremely low in DO (and a limiting factor for trout stocking) is now viable habitat with the addition of turbine venting.

A survey conducted by SCDNR in 1991 found that visitors participated in approximately 173,000 angler-hours of effort in the Hartwell tailwater and caught an estimated 172,995 fish, with the vast majority of these fish being rainbow trout. This study also valued the Hartwell tailwater fishery at approximately $800,000, based on angler’s expenditures.

The popularity of this fishery has expanded tremendously since the completion of the Lake Hartwell Tailrace Fishing Pier in January 2010. This pier, constructed by GADNR, is managed by the Corps. The funding came from a natural resource damage settlement with Schlumberger Technology Corporation, the responsible party for natural resource damages in Hartwell Lake. With completion of the pier, access to the Hartwell Tailrace fishery improved greatly. The tailrace is now accessible to all anglers, even those with disabilities.

Through cooperation to improve habitat, access and innovative management, SCDNR, GADNR, and the Corps have improved a unique fishery. When you think trout, you don’t have to travel to the mountains; you can catch them here in our backyard.

*For more information on the yearly physical changes of a lake, go to http://www.sas.usace.army.mil/lakes/hartwell/fishing.htm and select "Fact Sheet" under "Fishing Related Links".

Biologist,
Jamie Sykes

From Balancing the Basin, January 31, 2011

Water levels in the three Corps of Engineers reservoirs on the upper Savannah River change constantly – and with good reasons, according to the experts who manage the water in the basin. Changes in precipitation patterns, evaporation levels, and downstream flow requirements occur every year in an ecosystem like the Savannah River Basin. Even in years of abundant rain, the reservoirs will fluctuate up and down.

"It takes constant monitoring of data and adjustment to fulfill as many of the purposes of the reservoirs as we can," said Stan Simpson, a Corps water manager in Savannah, Ga., who helps oversee water flows out of the dams and onward downstream. "We must balance water supply, water quality, flood risk reduction, navigation, recreation, hydropower production, and environmental stewardship. It is our mission to meet these project purposes in an equitable manner within our authorities".

The "guide curve" represents the target water surface level for any particular day on the three reservoirs operated by the Savannah District – Hartwell Lake, Russell Lake, and Thurmond Lake. Many factors impact the Corps' ability to maintain the pools on guide curve including the natural inflow to the reservoirs from tributaries and the release of water from upstream reservoirs. The reservoir levels also vary depending on evaporation, transpiration, and groundwater interaction. Yes, even evaporation will cause the pools to fluctuate.

On the Corps' Savannah River reservoirs, guide curves vary by season. "The water level targets are lower in the winter to protect the shoreline and to prepare for typical spring flooding. The guide curve was designed to enable the reservoirs to successfully operate for a range of annual circumstances," said Jason Ward, another Corps water manager. Seasonal high winds in the winter and spring if combined with high surface levels would lead to shoreline erosion and add silt to the reservoirs, Ward said. Lower winter levels also give the Corps added storage capacity for normal winter and spring rains. This extra storage allows the Corps to be more successful in reducing flood damage downstream. "We can't keep the reservoirs level year round without causing some damage somewhere in the basin."

The three reservoirs sit on the border between Georgia and South Carolina - the two states that share the water. Lake Hartwell, the uppermost reservoir, has a guide curve that runs from 656 feet above mean sea level (ft-msl) in December then slowly increases to 660 ft-msl from April 1 through Oct. 15. Lake Thurmond, the oldest and most downstream reservoir on the Savannah, follows a guide curve from 326 ft-msl in December to 330 ft-msl for most of the year. Lake Russell, between the other two, has a constant guide curve of 475 ft-msl due to its design and smaller size. The water managers like to begin each summer with the pools at the summer guide curve level which helps them meet both in-lake and downstream needs throughout the typically dry periods in Georgia and South Carolina.

"Water management is dynamic, as is nature, always changing," Simpson said. "The guide curves were developed using many years of data and future updates will reflect changes in the hydrology of the basin. Our record of meeting the needs of the entire basin – upstream and downstream – is very good, in spite of its 'ups-and-downs.'" Reservoir information can be found on the Water Management web site at http://water.sas.usace.army.mil/home/indexDU.htm.