A Simple Observation And Reason As To Way Shadow Lake Dam Collapse Wasn't As Bad As It Could Have Been

Bill Stevenson is a life long resident of Middletown who lives adjacent to Shadow Lake. If there is anything anyone wants to know about the lake, he is the one to speak to.

Mr. Stevenson sent along, via email, his observations as to why the collapse of Shadow Lake dam was not as cataclysmic as it could have been, it seems that the precautions that were taken back in 1938, after the dam washed out a second time in 4 years, was enough to save it from total collapse 73 years later.

Mr Stevenson also expresses an idea on how to temporarily fix the road and open it back to traffic in a timely manner in the aftermath of Hurricane Irene.

The collapse of the Shadow Lake Dam has not caused the water level to drop even 1 inch below normal. Let me explain why.

The dam was originally constructed with a spillway at the south end. After the dam washed out twice (1934 & 1938), they added a 2nd spillway at the north side. This was a few inches higher than the main spillway, so that is only needed when the water rises. Beneath the earthen dam are interlocking steel beams which were pile driven into the earth to about the level of the spillway. In addition, a creosoted wooden bulkhead was constructed between the earth and the water. The top of this was slightly higher than the spillways.

Both the steel beams and the bulkhead survived the washout. Thus the lowest point was the original spillway. The beams may have been bent slightly, but I don’t think that it is serious.

Now as to what happened to cause the washout. This is what I believed happened.

The heavy rain caused the level of the lake to rise well above the spillways. I don’t know how much, but at the west end of the lake at Stevenson Park, the level rose about 3½ feet above normal. At the main spillway, the level was so high that the spillways could not handle it and water started to flow against the berm at the north side of the spillway. Once it had eroded a small portion of earth, the erosion expanded and got worse as it got larger, eventually washing away more than half of the top of the dam and eroding a big hole in Hubbard Avenue. I think that they should fill the hole in the road with large rocks & maybe concrete. There should not need to have a big rush to replace the washed out portion of the dam.

Bill Stevenson

Those are some good observations but it leave the question of why didn't the water go over the 2nd spillway also? If it had maybe Hubbard Rd. wouldn't have been damaged as badly as it has.

I suppose we'll just have to wait for that answer however and be thankful that it a total collapse of the dam did not occur or much more damage would have resulted.