Earlier we asked readers to pose questions they would like us to address in Balancing the Basin. One reader asked why Richard B. Russell Lake varies little in its level and if it could be used to protect the levels of the other two reservoirs. We get this question from time-to-time, especially during a drought when the levels of Hartwell Lake and Thurmond Lake decline.
The short answer to these questions: Planners designed Russell Lake to operate within a limited range, and that range was defined by Congress as our conservation storage allotment. Allowing it drop more than 5 feet below full pool can impact the efficiency of the turbines, but it also violates operating parameters that can only be chanced by congressional authorization.
The longer explanation: All three reservoirs have multiple purposes – hydropower production, downstream navigation, water supply, water quality, recreation, and fish and wildlife management. Hartwell and Thurmond have another, vital, purpose of flood risk reduction (originally called ‘flood control) that Russell Lake does not have. Instead, hydropower production sits at the top of the mission list for Russell Lake.
Congressional authorization and the design of the Russell Dam only allows for a 5-foot fluctuation above and below full pool of 475 feet above mean sea level (ft-msl). At levels above 480 ft-msl we endanger the dam’s integrity. At levels below 470 ft-msl we fall outside our authorized operating range and begin to lose turbine efficiency. But there is good news.
Russell Lake has eight power-generating turbines. Four of the turbines also have pump-back capabilities. They can run in reverse at night to draw water out of Thurmond Lake back into Russell Lake. This water can then be used over-and-over to generate low-cost, non-polluting energy. This saves water in the other two reservoirs while still allowing us to meet peak power demands in hot summer afternoons or cold winter mornings. For a visual explanation, please visit our You Tube channel at http://bit.ly/1kwtzkS.
Pumping water back into Russell Lake does cost money. When we pump water back the government must purchase commercial power to run the turbines in reverse. We do this at night when commercial power rates are lowest so we can have the water available during the days when demand peaks
Because of its relative small size, Russell contributes little to downstream water needs for the Savannah River basin. We must still rely on Thurmond and Hartwell lakes to meet those needs. That doesn’t mean we don’t draw from Russell during severe droughts. We have used its limited conservation pool to assist with downstream needs, but it is not a main source of water
By using Russell’s pump-back capabilities we can still provide much of the peak power demands during dry periods while mitigating water loss from the reservoir system. This helps protect reservoir levels at Hartwell and Thurmond while still providing power to homes and businesses throughout the southeast.
~ Billy Birdwell, Senior Public Affairs Specialist
Hi Billy, Thank you for this informative post! I have a couple of questions.
1. Is Russell’s drawdown limit of 5 feet because these turbines are different from those in Hartwell and Thurmond or because of the penstock (intake) design?
2. The data for the past couple of weeks suggests that the hourly pump back capacity being used is half of the design amount. Why is the full capacity not being used?
~Ferris
Hello Ferris:
Planners designed Russell Lake to operate within a limited range, and that range was defined by Congress as our conservation storage allotment. Allowing it drop more than 5 feet below full pool can impact the efficiency of the turbines, but it also violates operating parameters that can only be changed by congressional authorization.
Also, we don’t use pump-back unless we need it. In order to pump water from Thurmond Lake into Russell Lake, the Southeastern Power Administration must purchase electricity from the commercial power grid. We buy this power at night when the cost is lower so we can generate power the next day when demand is high and cost is high. Still, because it costs tax dollars to pump, we don’t run the turbines in reverse unless we know we need the power the next day or so.
Thanks for asking.
— Billy Birdwell, Savannah District
Thanks Billy, I appreciate the feedback.
– As much as I resent the delays and politics involved with Congressional approvals, the process hopefully promotes a comprehensive evaluation of most aspects of a situation and helps protect the less powerful. Also, congress does share responsibility for the budget, southeast power reliability, and the impact of changes to operations, both upstream and downstream.
– From some published industrial user rates I had expected summer peak power generation prices to be 4 to 5 times the off-peak pump back costs. For providers, I am now assuming that the ratio is not as dramatic. Is this ratio something that can be shared?
– Finally, am I correct in understanding that all operational issues have been resolved for simultaneously running all 4 turbines in pump back mode? ~Ferris
Thanks for using all four pump-back turbines! The Declaration and Projection dated July 30 show all four Russell pump back systems running simultaneously beginning Saturday for the next 10 weeks during off peak hours, with corresponding reduced release rates in Hartwell and Thurmond. Of course, the benefit is using the recycled water for additional generation. I have been unable to find where this has happened before. Operating in this manner will reduce the rate the lakes drop while keeping a little more than the minimum downstream flow rate, at least until Drought Trigger Level 1 is reached. But reaching Drought Trigger Level 1 will take a little longer. ~Ferris
As I recall, the Russell project was initially accompanied by much debate over water quality and fish. Has the addition of underwater oxygen injection resolved the DO issues for the fish? Does the hydropower generated by Russell cover the cost of this oxygenation?
Also, at startup there were serious fish-kill issues on Russell’s puimp-back and it was stopped for a good while. Since it has resumed, I assume that changes made to protect more of the fish population. Can you or a fish and wildlife person comment? Thanks!
Thanks for your comment–you bring up some good questions. We have an upcoming post scheduled within the next few weeks addressing the oxygen system at Thurmond Lake and it’s effect on pumpback at the Thurmond Dam. We will address your questions in that post, so stay tuned to Balancing the Basin. Thanks for reading us. ~Tracy Robillard, public affairs specialist
Am I seeing things or last night did Thurmond release water at the same time Russell was pumping back? I would love to know how that is a good practice since just leaving the water in thurmond and using it later would accomplish the same goal. Also, is one of the 4 pump back units permanently broken? I’ve noticed only 3 or 2 have been available all summer. Is this the reason release rates had to be raised back up to 6700cfs from thurmond this week? (Since pump back can’t be maximized?).
Scott: We generated at the Thurmond Dam yesterday through 9 p.m. while Russell pumped back from 11 p.m. to 4 p.m. (Central Time)–they were not operating simultaneously. The Thurmond 6,700 cfs outflow rate is currently necessary to keep the pools in balance based on inflows to the system. We are working on repairs to one of the pumpback units but anticipate bringing it back to service in September. The increase at Thurmond is not directly related to pumpback. ~Tracy R.
So no inflow to Hartwell = more outflow from thurmond. Gotcha. But you can’t create power by reducing demand and generating more power at Hartwell and thurmond has nothing to do with reduced generation at Russell.
I guess the hardest part I have with the whole strategy is that for this first 4 feet, the release rates at thurmond and Hartwell have ABSOLUTELY NOTHING to do with inflows, levels, downstream rain events, or expected rainfall.
Scott: Thanks for your thoughtful reply. Where are you getting your data on no inflows to Hartwell? A query of our daily inflow data shows daily average inflow at Hartwell through the last 7 days, as high as 4,585 cfs on Aug. 21. The average increase in outflows at Thurmond this week was relatively small, with rates increasing by 100 cfs. I challenge your statement about managing the first 4 feet of conservation storage. Yes, hydropower is definitely a part of the equation, but we also factor in inflow volumes (including rainfall and releases from other dams/projects) and environmental & municipal demands. For example, if we had normal pools but below normal inflows, and let’s say there was no hydropower demand, we would still have to release a minimum amount of water downstream to supply a wide array of downstream uses. ~Tracy R.
Hi Tracy, What I notice about the projection is that those of us downstream are reduced to drought level release rates before the basin reaches Drought Trigger Level 1. I think it is the right call considering the rainfall shortage, but those on the lakes are receiving “preferential treatment”. Some on the lakes insist that 3600 CFS works, but that just shows they have not bothered to read and understand the science for the whole basin. ~ Ferris
My comment if based on the “balancing” comment. Which can be read Thurmond > Hartwell or vice versa. I will digress.
But for weeks the releases were being held at around 5500-5800cfs from Thurmond. During this time inflow to Hartwell has been averaging 2000cfs (not doing math, just looking at numbers), Russell is negative not counting Hartwell releases, and Thurmond is around 500cfs. So hey, even though lake levels are 3 feet below “full” and inflows are only 2500cfs and lowering, let’s up releases from Thurmond to 6700cfs (8/20 declaration) and 7600-7400cfs (8/27 declaration). Let’s make sure that for the 5th year out of the last 6 we get to the drought trigger at then end of September.
If you are always hitting your drought trigger, even in years that don’t have drought, MAYBE you should reconsider your plan.
As for Ferris, I understand he thinks the lakes are getting “preferential treatment” but what would downstream flow be right now WITHOUT the lakes. If you look at inflow, I would estimate it has been <4200cfs since EARLY JUNE. I understand you want us all to "share" and I'd be fine with that if there wasn't this pesky minimum release rate than must be maintained even if inflows become almost zero. Because other dams operate that way, after the level drops to a point, nothing goes downstream until they recover.
My suggestion would be to establish a Thurmond release rate based on total storage (AC-FT) in all three dams. You could even drop Thurmond first this way. As the releases from Thurmond decrease, you'd have to make up for the generation with more from Hartwell and/or more pumpback (though I believe you should always pump-back, it just makes sense), with the goal of both Hartwell and Thurmond reaching Trigger 1 at the same time. Eliminate this silly "balancing the pools" thing that results in one week of 4600cfs releases followed by the next week at 6800cfs. This would be much more easily explained.
For the record, I use Thurmond lake, this lake I'm suggesting for the first drawdown under my "scheme" because you make water run downhill, but you can't put it back in Hartwell once it leaves.
Hi Scott, Please note that the “pesky minimum release rate” is required. Just like homes on the lakes have changed lake level considerations, development downstream has change river flow rate considerations. There are over 200,000 people and many industries downstream that not only depend on reliable river intakes but have a legally permitted right to them. Obviously the industries employ people, and a couple generate power. Eliminating their source of drinking and process water is not an option when there is any other alternative. Presumably they are not on this blog because they don’t have to be. If their water source is threatened they will probably initially go to the same representatives with which lake users are failing to get traction because they have a valid legal position. If that fails they could take legal action. Regards, Ferris
Hello to you as well Ferris,
I normally consider your posts quite on target but your continued inference that lowering the release rates to minimum prior to both Thurmond and Hartwell reaching drought level 1 is “preferential treatment” and the false graciousness of it being the right call “in this case” got me a little riled.
I understand perfectly why the minimum release rates exist, but to suggest that business, industry, and drinking water are the true basis of the minimum is to forget the oxygen content and other so-called “environmental” concerns significantly increase this “minimum” flow. That is why the minimum is so much lower in the winter (cold water can dissolve air better). Also, see which groups complain the most (it won’t be Georgia Power, which will be the largest user if it isn’t already) if you want proof of who is setting the minimum.
So I can only take so much of your complaining about how downstream users are being “hurt” by the Corps’ management of the lake, when come rain (exculding last year) or drought, the Corps always seems to hit drought level 1 at the end of summer.
Looking at the past 6 years of data, the downstream flow has only been reduced in summer when the lake didn’t fill up in the spring, but it is then reduced in the fall (since the trigger is achieved in early to mid September). I would think that a slightly lower release rate in July-August would make for a more even flowrate downstream year-round. I would call it a win-win for us and a lose for the Treasury. But hey, they really need to make that money by making more hydropower in the summer (as it sells for a lot more.)
Scott, the minimum flow needed for environmental demands is directly connected to increased populations and industries downstream. Georgia and South Carolina control the amount of industrial and municipal discharge of treated waste water into the river through permits. The states base their permits on the minimum release rate of 3,800 cfs, which ensures enough dilution to maintain the water quality. Treated waste water reduces the amount of dissolved oxygen in the water, and based on this discharge (which has the potential to impact the environment) there are set minimum releases to ensure dilution. So with a natural river (no lakes & no human populations) the lowest natural flow would still be able to sustain the environment because human activity would be removed from the equation. With this in mind, business and industry and drinking water *are* the true reasons behind the minimum flow. Hope this helps. ~Russell
Hi Scott. I appreciate the continued dialog even though my sarcastic statement got you riled- that is on me.
– The 2012 Drought Plan shows the same release rate for Trigger 1 all year long with only the Trigger Level changing for the winter drawdown. Trigger 2 is worse for everyone and does provide for an additional release rate reduction from Nov 1 -> Jan 31. Dec and especially Jan are generally wetter with less transpiration loss than Oct and Nov, so my guess is that improved runoff conditions and more rainfall help offset the additional release rate reduction. Triggers 3 & 4 require special permission for an extra release rate reduction.
– DO is very important and warm water loses DO faster than cold water, as you stated. Municipal and industrial wastewater does need DO to be assimilated into the river water. However, DO does not appear to be an issue until reaching Trigger 2 based on the release rates discussed above, assuming as you do that the reduced rates are related to DO levels.
– My read on the previous Comprehensive Study information is that river intake levels determine individual river flow rate requirements rather than intake flow rates themselves.
– Environmental issues are a concern as you state, and are probably the factor inhibiting a concerted effort to lower intake levels. Environmental issues cover a wide range of subjects. In the forefront, adequate DO to assimilate wastewater will quickly become a limiting factor if our assumption above is correct. Without adequate DO, the populations of game fish and other species would be decimated. Without adequate flow rates, the river stays in the channel while oxbows and side channels become stagnant or dry, decimating nurseries and reproduction areas for game fish and other species.
I hope these comments help you understand my thoughts. ~Ferris
Ferris,
Sorry if I was too harsh. My overall concern, is that the corps plan (which is mainly driven by jerks I’m Congress), gives only lip service to the concerns of people who use the lakes and rivers (Their actions prove hydro and lake “balancing” rank higher than your concerns or mine.) Every day since June that they released more than 6000cfs was less water to maintain true downstream quality. (3800 represents bare minimum standards which is why it is not invoked at trigger 1). AND it lowered the lakes faster. The only goal of the corp it met is hydro ($) production). Now given the rainfall this past year, i am grateful we havent yet reached trigger 1 and believe that they have done a better job than in the past, but that is not saying much. Let’s both hope for decent rain this fall and/or winter.
One more suggestion:
If you don’t commit to as much hydro production on weeks with a holiday day, you could produce more on weeks without. As I know that electricity does not cost as much on a holiday (it’s essentially a weekend day and that’s why you don’t produce as much energy on Saturdays and Sundays), if you had a slightly lower commitment on weeks with holidays, you could use that time for additional pumpback / less release from Hartwell with a minimal impact on dollar production for the Treasury. On years with drought, it might even increase your dollar production, as you would be able to produce more power before reaching trigger 1.
I was looking at the most recent declaration. During periods of high pumpback (currently 21 unit-hours per day is declared), it raises Russell’s level almost a full foot over the weekend. Based on this, why is the target level on Friday for Russel 454.5 feet? This would result in Russell being 1/2 a foot over full on Monday. Wouldn’t lowering the Friday target level for Russell be more consistent with actual operation and ensure that overall inventory loss from the basin is minimized?
If applied to next week’s declaration, wouldn’t releasing Russell down to 474 feet vice 474.5 would result in approx. 2000cfs more flow from Russel per day. This would then result in lower releases from both Hartwell and Thurmond, conserving water inventory.
Russell would still be within 1 foot of full the entire time, and would be at almost full pool on Monday. As it stands now, if pumpback the weekend of 9/20-9/21 is equivalent to the pumpback scheduled for this weekend, Russell will be at 475.2 feet on Monday 9/22.
As Hartwell and Thurmond levels have only been maintained constant with recent rains, it concerns me that the release rate from Thurmond is being raised to 5600cfs next week. As trigger one levels are 4200cfs (and Thurmond level has dipped briefly below that this past week), this additional 1400cfs per day represents about 2.5 days of flow.