Savage River Dam Repair - Info
Thursday, October 29th, 2009Contributed by Jay Sheppard - Vice Chair, Conservation, Mid-Atlantic Council, TU
Info as of October 2, 2009:
MDE placed this project at the very top of all the Statewide projects (>300) to be funded by the Stimulus Bill passed in March. Contracts have been awarded for the construction of the new stainless steel gates to a company in Massachusetts. Original repair costs were estimated to be $6 million, but the bid that was accepted last month was for only ~$4 million. Here is the anticipated release schedule for the Savage Dam to eventually empty the reservoir to allow for repair of the main gates at its bottom:
Early October –31 October 2009
100 cfs plus average inflow (usually ranges from 10–100 cfs). Reduce pool elevation of reservoir to 1410′ (normal winter pool is ~1430′, spillway is 1468.5′; pool elevation on 2 Oct 2009: 1443′)
1 November–15 November 2009
Average inflow will be released during this period to keep the pool @ ~ 1410′. Probable range of release might be 35–150 cfs…but hard to predict.
16 November–31 December 2009
60 cfs plus inflow to empty reservoir completely by end of December.
1 January–18 March 2010
Inflow = outflow….run of river, no control whatsoever of any water coming into reservoir. The lower river and all tributaries likely to freeze over for extended periods of time; flow may be as little as 10 cfs or as much as 200 or more depending upon weather.
19 March–May 2010
Refill reservoir; not clear what the release flows may be at very beginning, but likely in the range of 30–60 cfs, with all excess inflow being retained within the reservoir once inflows start exceeding that ~outflow. Will depend upon storm and melt events. Refill will start earlier if the gates can be placed into operation sooner. The goal is to refill the reservoir by capturing as much cold water as possible before the inflows exceed ~50º F.
General notes re repair: Likely to be some muddy waters below the dam at times during this whole process. Most likely this will happen during the last half of December and during the spring melt of any snow pack.
All fish in the reservoir will be flushed out into the Savage River below the dam during the final stages of this draw down (e.g., end of December). How quickly these fish make it to the North Branch and downstream from there will depend totally upon the flows during the end of December and through the winter. Likely large numbers of walleye, smallmouth, largemouth, smaller panfish, minnows, and other fishes will be trying to find refuge in some of the larger deep pools of the lower Savage until flows are sufficient to move them down river. The adult browns and brook trout already in the lower river should be able to over winter in those same large pools in reasonable numbers to allow the trout fishery to rebound over the next year or two after refilling. DNR is planning to move several dozen adult brook trout out of the river channel immediately below the dam and place them in the stilling basin below the dam’s spillway. When spilling occurs next spring, these brook trout will be free to return to the main channel.
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Info from July 28, 2009:
A public meeting was held at the Bloomington Fire Dept. last week with a presentation by MDE, DNR, & ICRPB. A fairly detailed report was given as to how the repair of the dam was to proceed. Attached is a copy of the schedule for the draining and refilling of the reservoir. Basically, from about 1 October until about 10 November the reservoir will be lowered to an elevation of 1410′ (spillway is @ 1468.5′ and normal end of summer pool is in the range of 1430-1440′). The precise release during this first phase of the drawdown will be dependent upon what the pool level is on 1 October and any storm events. If we are in a drought, it might only be 35-55 cfs; if there is a lot of water coming in, it could be 60-90 cfs. Hard to predict at this time.
From Nov. 10 until about Nov. 25, the pool will be maintained at 1410′ elevation so some preliminary work in the tunnels can be accomplished. During this couple of weeks, a gate in the dam will be removed, carefully measured, and returned to its position. This is so the final touches on the new stainless steel gates will can be made before their delivery to the dam. The four new gates should last indefinitely compared to the current iron gates that have rusted very severely over the past 60 years they have been in place. During this stage, the day time flows will be about 10 cfs while workers are in the tunnels. After the works stops each day the flows will be equal to the inflow or slightly more if they are well over 10 cfs. Flows into the reservoir in November can run from 5-75 cfs, with a short lived peak of a few hundred cfs after a major rain storm.
From the end of November until the end of December, the reservoir will be drained completely so that when completed, what flows into the reservoir flows out. There will be no control possible on inflows or outflows after this time. If 5 cfs flows in, 5 flows out, if 300 flows in then 300 flows out, etc. Again, as in November, during the work days in December, the release will be about 10 cfs for workers safety in the tunnels under the dam. After working hours, the flows in December are expected to run about 60 cfs, plus whatever the inflow has been that day. There will be no refugia of any depth expected in the reservoir’s exposed channels for any numbers of the fish resident there to over winter. Those fish (mostly minnows, smallmouth, panfish and some walleye) will be flushed into the river below the dam.
They plan to have actually replaced two of the four gates by the time the reservoir is completely drained–about the end of December. The plan is to have all four gates completely replaced, along with associated hardware no later than the first week or two of March 2010 when refilling of the reservoir will commence. Late March and April are typically the wettest months and should capture a large quantity of cold water for the summer of 2010. I have sent my personal comments to MDE re the permit they will be issuing next month that there needs to be some incentive in the contract for early completion and significant penalty for lateness in starting the refill due to the repair.
DNR has no plans to attempt any removal of any of the reservoir fish after they come through the dam. Eventually they will either be caught by fishers, eaten by larger fish in the river, or move down and into the North Branch below Bloomington. There are going to be a lot of minnows, shiners, etc., washed into the river that will be easy prey for any large browns!
Fishing below the dam from October through next March should be fine until such time as the fine sediments are mobilized and muddy up the river. My guess (and only a guess!) is that this may happen sometime in November and may last until the reservoir is drained and the banks of the exposed reservoir stabilize and freeze. It is very hard to estimate the sediment load that will be sent into the river during this repair. It will certainly be considerable. The smaller sands and small gravels have been almost totally absent from the lower river bed since the dam was placed into service in 1949. I hope we can go several years post-repair before we have any really big flood events that will flush this material further on down and into the North Branch. That may allow some of the sediment-loving macroinvertebrates to establish a sizable population below the dam for several years or more (e.g., green drakes). There should also be better spawning sites for the trout for several years. I am also hoping that the introduction of a lot of small fish into the river will make for some big browns next summer. This is all conjecture and only a relatively informed opinion. We must all remember that the lower Savage regularly had flows of 10 cfs prior to 1983 when Jennings Randolph Dam came on line. Those of us who fished the river at those very low flows found lots of trout…many just as uncooperative to taking our flies as they are now (must be genetic!…or fish do really have schools!) In very cold weather we should expect the river to freeze over.
In final summary, I do not expect any major loss of wild trout in the fishery below the dam. There are a large number of very deep pools in the lower river that will serve well as refugia for the trout. The choice is either repairing all the gates during the winter or having a gate failure at some point in the next few years. The new gates will give our grandchildrens’ grandchildren a good fishery. We should be thankful that the 2009 Stimulus money became available for this $6M project at just the right moment!