We couldn’t make the meeting over in Ennis last Thursday regarding the final story from PPL and FWP on the dam and management issues with the Madison. 

Mike over at Madison River Fishing Company in Ennis did put up some interesting comments about what actually happened and what the further repair plan is at this point….

It was initially reported (and, in fact was continued to be reported for some time) that two of a set of four intake gates had failed. That was not correct. There are, in fact, only two hydraulic gates that are part of the structure not four. There was never a failure of the gates themselves. Basically the intake tower is a ~75’ tall concrete shoebox sitting on end a hundred feet or so from the dam itself. Three sides of the box are solid and the side facing the reservoir itself is open. There are four “bays” on the open side which really means that there are five vertical “piers” in front of the open face of the tower effectively splitting the opening into four. The interior of the tower is split into four “chambers” as well but there are huge holes in the walls (not from damage but as part of original construction) allowing water flow throughout the tower. The piers create channels between themselves and the face of the tower to allow for the stoplogs and, in bays one and two, the hydraulic gates, to be slid into and held in place holding back the reservoir. Bays three and four, the ones on the right side of the tower when facing it, are blocked completely with timber stoplogs from top to bottom. Gates one and two, the ones on the left, are blocked at the bottom (starting about 75 feet down or so) with concrete stoplogs. Then what appears to be at about 30 feet up or so are the hydraulically controlled gates. There are a few more concrete stoplogs above the gates; it then transitions to timber logs again going to the top of the structure.

The failure occurred in bay four at about 30 feet or so down. 17 of the timber stoplogs “disappeared”, most likely rotted and were sucked through the tower, through the dam and out into the river below. The plan right now is to shore up the “repaired” face of bay four and bay three and send divers down to try and figure out exactly what happened. They will then go back for a more permanent fix in the spring after the lake (hopefully) is full again. The plan is to divert the flow to the spillway and dewater the intake tower allowing crews to replace all of the wood stoplogs with concrete “logs”. This will give a much more “permanent” fix.

PP&L was able to regain flow control with about a foot or so of reservoir water elevation over their March first drawdown level. It ended up being very close to where we were at this time last year, maybe a hair lower. Not much cause for panic at the moment. As I said in my last report, if they play it correctly from here forward they shouldn’t have a problem filling the lake again. From the flow right now it looks as if their plan is to keep the level static for the winter and catch all the snowmelt they can come spring. We’ll need an average or close to snow pack this winter to make things right again but we tend to count on that most winters anyway.

Good news for the most part, at least compared to what it could have been….

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