FURTHER THOUGHTS ON IDEAL DROUGHT PLAN

The previous post presented our proposal for the ideal drought management plan. Basically the plan is to maintain a constant level on Lake Thurmond until rain inputs cause the release rate to drop below 3600cfs. At this point hold release rates at 3600 cfs until rain fall permits operation at full pool with a release rate in excess of 3600 cfs.

Since publishing that post several other positives to this approach have become evident:
1) this would return the Savannah River below Thurmond Dam to the flows it used to have prior to the dams with the exception of avoiding the ravages of floods and droughts.

2)3600 cfs is the flow equivalent to the average annual rainfall during the droughts of record. At that release rate we should not lose the lakes regardless of how long the drought continues. Any higher flows could empty the conservation pool of Lake Thurmond and destroy the basin if a drought goes on long enough. Basically the reasoning is you can not spend more than you have coming in without going bankrupt.

Drought Management Plan for Lake Thurmond

For the purposes of this post I am presenting my idea of the ideal drought plan for Lake Thurmond . Treating the operation of the dam as a standard engineering problem it really is quite simple.

1) Keep lake levels at full pool to within a few tenths of a foot as long as there is enough rain to do so. This capability has been demonstrated by years of balancing Lake Hartwell vs Lake Thurmond.

2) When release rates drop to 3600cfs allow the lake level to fall until rainfall permits maintaining a full pool again.

3) As part of maintaining lake levels as close to full pool as possible river flows following a rain event should be monitored to allow dropping below 3600cfs when possible.

The philosophy behind this plan is that all parameters the Corps is charged with for the Savannah River Basin can be maintained as long as there is plenty of water in the lake to give acceptable river flows. In the past lake levels have been permitted to drop with low rain fall. The trigger points for reducing releases from Lake Thurmond Dam were too low and the release rates called for allowed the lake to continue dropping too long. Had the drought of 2008 continued a little longer we could have lost the whole basin. This is simply unacceptable.

The biggest objections I have run into to date with this proposal is whether 3600cfs is adequate for downstream needs. I picked this figure for the following reasons:

1) no downstream stakeholders had any problems from a 3600cfs release rate that continued for over 12 consecutive. That being true why not use 3600 unless some problem rears its head or until more detailed studies can be completed.

2) the industrial release limits along the Savannah River are based on 3600cfs.

3) 3600 appears to be adequate for the Short Nosed Sturgeon.

4) detailed analyses of oxygen demand along the Savannah since 1977 show that reducing releases to 3600 in 2008 had no deleterious affect on oxygen level at Clyo which means no effect on the harbor either.

Downstream stakeholders will probably interpret this plan as selfish interests by lake stakeholders. In reality though this is the only way to protect downstream interests from being devastated should lake levels drop so low that adequate river flows can no longer be maintained. Looking at the parameters the Corps has been charged with (flood control, hydro power, navigation, recreation, water quality, water supply, fish and wildlife, economics) this is the only way to meet all these. With the current drought plan recreation and economics are destroyed quickly in a drought. All the other parameters are lost if you ever reach the bottom of the conservation pool.

Some will argue that hydropower is lost but SEPA has repeatedly assured us and the Corps that they want the lakes to be as full as possible. From their perspective they can reduce power production and spread the burden on others without any major problems. What would devaste SEPA would be lake levels so low they can no longer produce power.

This plan will work equally well if we decide some higher release rate has to be maintained. Simply insert that release rate into the equation and the rest remains unchanged.