Case in point, the Yellowstone River, Montana. The ‘longest undammed river in the US’, except it has 5 or 6 low head diversion structures. Some completely unmarked, and, most have passages, but which side of the river? The event horizon is often not at all evident. Gotta know where you are and have asked locals for advice. There ain’t no substitute for local knowledge.
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Sad case. The bottom at the boil would be solid concrete, definite head injury risk. Two years ago:
Sort of falls under the category of attractive nuisance, which is why they have to fence in swimming pools. The powerhouse isn’t blocked at all.
I’m surprised this 25 foot drop is considered to be a low head. We had another drowning a few years back at Flook Dam which I would consider low head.
Also not sure we need to rename the Huron River to Heron, although there are a lot of 'em on the river.
Perfect. Thanks !! The one difference is, the water flow shown in the video is a rare springtime high water flow, my guess looking at the video and still shots that is 800 cfs or greater. The Ford dam is subtle, really subtle. The usual flow is less than 200cfs and the water comes over so smoothly, the drowning zone almost flat to the boil, just a few bubbles… smooth quiet, placid, deceptive because boy can it kill. The thing not shown or discussed in the video, the boy’s canoe was snapped cleanly in half. Just snapped. That smooth deceptive kill zone tore that canoe in two like it was tissue paper. Which leads me to believe, the canoe did not come up flat alongside. The bow or stern area of the canoe contacted the dam face momentarily. The one end filled so fast to be taken down the stern paddler was most likely looking at half a canoe
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A good point was raised about what happens when one plunges down the drop at one of these dams. Many of these dams have a substantial drop, the water on the downstream isn’t very deep, and under the water you may have a concrete slab or rocks. Perhaps many of the fatalities attributed to being caught in the roller are actually primarily due to loss of consciousness in the water after hitting something?
Do you know or were there eye witnesses who said that the canoe was torn in half immediately?
A lot of times boats stay in those hydraulics for a long time getting tumbled and it may have been destroyed after the immediate accident.
Perfect keeper hydraulics entrain a lot of woody debris like trees, branches and limbs. They get stuck in there and do not come out. So not only do people and their boats get stuck in a maytag, they get thumped by all of that wood.
Even if the current is only 2 mph by the time a paddler gets close to a dam they need strong and smooth backpaddling skills to stop the boat and make it back up and if they don’t dump just above the dam trying to stop then bumping the dam could easily put people in the water in a very bad place.
What if the river is lazy and the current is only about 1 mph? Seems like the vast majority of paddlers (and tubers) could deal with that and avoid going over a dam even if they get close?
From above it looks scary - infinity pool with a drop beyond it and the critical chunk is hidden from view until you are on the lip. From below it doesn’t look dangerous unless you know what’s going on. So I suspect most incidents involve people approaching from below.
The pool has no appreciable current - its a backwater - until you get close to the spillway. But, by the time the water reaches the lip it has accelerated to a pretty good clip, far more than 1 mph.
That is scary - didn’t even want to watch it.
Lots of dams like this around here - why would you paddle up into the boil from below the dam - sad. Still, I wouldn’t call that a low head dam. To me a low head dam has less vertical drop that lures people into thinking that they can run it - like the dam in the tdaniel video. Paddling into the hole from the bottom is a different problem.
One might paddle up to the dam face because it looks interesting or might think it fun and mistakenly believe it is more benign than real rapids.
In the case study I cited above, 3 of the incidents and fatalities involved canoe/kayaks. Eleven of the 24 incidents and 15 of the 30 fatalities involved fishing. It is common to fish at the turbulent water in and round dams.
ASCE defines low head, also called run of the river, as a dam across the width of the river and which spills uncontrolled over the dam. Typically up to 15 feet but there is no hard limit. My speculation is the practical limit has more to do with increased engineering, cost and the utilitarian intended function of the dam. Nothing to do with boats.
I think it can only be because of the deceptive benign appearance of the hydraulic the dam creates and a complete lack of appreciation of the risk.
Assuming the description of the accident is correct, it is very sad that the two youngsters and all the kids on the trip were not made to understand the danger.
Wow - by that definition almost every dam around here is a low head dam. There are 11 dams on the RI section of my home river the Blackstone, and all but two (Woonsocket Falls - an ACE Flood Control Dam, and Pratt Dam - unblocked tubes through the dam) would be low head dams.
Most of the pictures are in low water, but every one of them is dangerous if you approach from the bottom. I can only think of one fatality with these dams - father and son in a tandem canoe dumped trying the run the tubes at the Pratt Dam and the son got hung up in debris and drowned.
Interesting - I always thought thought of low head dams as being lower. In a way it does’t matter - they are all dangerous .
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Agreed - very sad.
I think that ‘low head dam’ isn’t a good term. Head is basically the water depth behind a dam, so pretty much every low dam will also be low head. My understanding is that ‘low head dam’ is intended to refer to a dam which:
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Spans most or all of the width of a river,
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River flow normally runs over the top of the dam as run-of-river flow (rather than a through a spillway which goes through or around the dam),
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The water on the downstream side of the dam sometimes creates a hydraulic roller, and
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The dam is low enough that a significant percentage of river users might think it’s safe to go over the dam or get near the turbulent water on the downstream side.
Perhaps a dam with a drop of several feet or more shouldn’t be called ‘low’, since a significant drop can be dangerous even if there’s no roller.
A more precise term would be something like ‘low run-of-river dam’.
With current environmental and economic concerns, very few dams are being constructed. In fact it’s just the opposite. In many areas dams are being removed as funds become available. Many of these dams were built long ago to supply water power for mills and to enable logging.in areas with no good road access. These are generally no longer needed and have largely been abandoned. No longer maintained these obsolete dams inhibit native fish migration, create a hazard for people on the rivers, and pose a danger if they fail.
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We will always have the low head dams on our major “industrial navigation” river channels here in SW PA. Could not have barge traffic on them without the pooling depth the dams create.
Before the dams we have on that river system, people could wade across the mighty Monongahela (which joins the Allegheny to become the Ohio the feeds the Mississippi). In fact, just today I drove over the hill to the adjacent town of Braddock, PA, for the local history museum’s commemoration and re-enactment of “General Braddock’s Defeat” there on this date in 1755 during the French and Indian War – there are paintings in the museum illustrating the British troops wading across the rocky shallows of the river on foot in water only up to their chests.
I agree with rstevens15. I used to work on a lot of projects with the US Army Corps of Engineers. In the early days 70s and 80s their offices were dominated by engineers and dam builders. There was a small environmental group. By about the year 2000 the ratio and flipped and most of the employees were in the environmental department.
Dams are coming out and the rate of recovery of the affected ecosystems has surprised people. The Elwah River in Washington is a classic case. The salmon fishery is recovering, the sediment is being removed during high flows.
The South Platte River in Denver is a good example of a paddling river that now has weirs and passageways for paddlers. It is accessible by a lot of people, and the cost has been accommodated. I lived there years ago in the 1980s. Great place to paddle after work in moving water and practice maneuvers.
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Hi All,
its a long string and I didn’t have a chance to scan all posts to see if this site was linked, but here’s a site/group where they are attempting to inventory all low head dams in the US:
hope that’s helpful!
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