A New Danger

The dangers that a spring thaw once meant for the Redridge dam included the possibility of a dangerous over-topping. The water level in the reservoir would get so high as to flow over the top of the superstructure itself, spilling down onto the dam’s foundation and threatening to wash away the entire structure. When this same scenario happened in the 60′s, the owners of the dam cut large holes into it in order to keep this from happening again. In the process however, they managed to make the situation just as bad. Now during spring thaw water flows through these holes and over the top of the dam’s foundation, slowly eroding away the concrete foundation. Perhaps the danger of a catastrophic failure was eliminated, but in the process the dam’s future was forsaken one spring thaw at a time. See the Big Picture >

The problem starts here, at the series of holes cut into the superstructure. Normally water is discharged through the dam’s own discharge pipes located at the base of its foundation. In high water, like springtime, these pipes can’t keep up with the flow. The water then flows through here, down onto the dam’s foundation and over its support structure. You can see some of the damage here, the second pair of metal rods (in the middle of the photo) have already bent due to the water pressure.

The torrent of water slides down the concrete foundation then slams into these support pilings. As you can see from the first piling on the left, they are quickly eroding away as is the foundation they sit on. Under the waterfall sits the discharge pipe shut-off valves, which take the brunt of the flow.

The waterfall moves between the two main support columns which hold the dam upright. Across the way you can see the other side of the dam, as well as some damage to the stairs and concrete footings on that side. These girders hold up the largest portion of the dam which stands over 70 feet above our heads.

Before falling off the foundation and into the river below, the spring flow first slams into the second row of supports. These six supports bear most of the dam’s weight in this middle section. These have faired somewhat better then their cousins further upstream since most of the water’s energy was dissipated on them.

Past these lies a drop of a couple of feet off the foundation to the river below. The discharge pipe outlets are underwater at this point. Far beyond you can see the culvert under the road that the river runs on its way to Lake Superior.

10 comments

  1. Nice photos of the old gal! I used to have an entire site devoted to it, but it was on Geocities. So when that closed, the site went with it and I never bothered to find a new home. I would like to correct something that you wrote though. The holes were not cut until the early 80′s. Partly due to the overtopping danger, but also due to the current roadway through there buried the waste weir. For a long time, there were only 4 holes in the dam. They cut the other ones at about the same time that they demolished the top half of the timber crib dam.

    • Thanks for the correction! It’s a beautiful structure even with the holes cut in it. If you got any old photos or stories of the dam from your old site, I’d love to share them with my readers. The dam is a favorite topic of many here on the site.

  2. Mike,

    The photos were very similar to yours — and the speaker specifically said “these aren’t mine, I found them on the internet.” I didn’t see or hear any credit otherwise, though. I couldn’t say for sure that they were exactly these, but they looked a lot like it. I also don’t know of other “spring runoff at the dam” photos online.

    The upshot of the talk was that even at current erosion rates, the steel dam is most likely safe for many years to come — the calculations were interesting.

  3. dcclark…

    wait a minute – they used my photos? Or did you just mean they used photos similar to these…If they used mine I hope they at least gave me credit…

    Obviously the dam is stronger then anyone expected, but this continuous barrage of spring runoff can’t be good for the concrete footings seen in these photos. But since the dam doesn’t hold back water anymore, even with a few of these posts failing the whole thing would probably keep standing.

  4. I believe that a number of these photos appeared in a presentation which I just saw, about a MTU senior design team which studied the dams.

    The result, generally, was that the dams are much more stable than expected, and likely to last for many years, even without maintenance.

  5. Herb..
    I think we found the same trestle, if its the one by the road. We also found the concrete retaining wall which was from the dam’s spillway. When the new road was built downstream from the dam (the original road ran up closer to the dam itself) they filled in the spillway making it useless. It is a great place to explore, hopefully it will stay accessible for decades more.

  6. We camped at the Redridge Dam in late August. Wanted to camp on the stampsands but it’s all private and posted there now.

    Walked around and found a steel RR trestle or bridge back in the woods. Also some concrete retaining wall that appeared to form some kind of overflow spillway from the old lake.

    The old wooden dam ruins (next to the steel dam) that appeared after the lake level dropped is also pretty cool. At least you can still camp there.

  7. Geoff – There is no current efforts (at least to my knowledge) of any one attempting to rehabilitate the dam. The national trend is for all dams that have outlived their usefulness to be removed for environmental reasons. I am sure the debate will soon hit this dam in the future when it becomes necessary for the township (Which owns the dam) to take action to stabilize the structure. I have a feeling that its unique character will probably save it from the scrap heap (since it is 1 of only 2 left on the continent). But you never know.

    But in all seriousness the spring thaw’s have been roaring through here for almost 50 years now, and the structure still stands. And by the looks of things close up, it probably has some good time left until things become a problem. I just hope something is done before that happens – its one of the most interesting sites around the CC.

    Casey – Thanks for joining us! Your photos are great and provided a glimpse into an area (one of the few) that I have yet to explore – the Baltic Mill. Since you said its been a few years, you must no longer be around to do any exploring for yourself anymore. Hopefully this site will fill the void :)

    The lake looks just as awful as you remember. Not much has gown in yet and the shoreline is littered with debris. We even stumbled upon some have buried canoes and destroyed boats along the way! Most likely the trees and brush will return I just don’t know how long..

  8. Are there any efforts to restore the foundation and maintain the structure??

  9. Wow, I had no idea this site existed. Also didnt know anyone was checking out my pics. Excellent article here. If only the site could be restored, or at least preserved. The scar on the landscape when the lake was lowered looked aweful. I havent been there in 2 years, I hope nature has recovered.

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