Yellowstone dams

[mdunc8]

Let's move the discussion over here so this doesn't serve as a distraction from the other thread.

For simplicity, dams = weirs and weirs = dams. Functionally, they both limit passage. Some more than others.

Is the Yellowstone River technically dammed? Yes. There are many low-head diversion dams that limit movements of certain fish at all times or most fish at certain times. With the exception of years where we have huge spring runoff, 2011 and 1996 come to mind, Intake prevents pallid sturgeon, paddlefish, and a handful of other species from passing. During baseflow, it makes it much more difficult for most species.

There are several dams (e.g., Huntley) that are made of concrete that also limit passage.

Some of the dams have side channels, some natural and some manmade, that permit fish passage during certain times of year.

Nothing on the mainstem river regulates discharge though. Some tributaries (e.g., Tongue, Bighorn) have large reservoirs on them. Those dams regulate discharge for flood, irrigation, and recreational purposes. The effects of those dams are significant, even on the Yellowstone. For example, a substantial range reduction of sturgeon chubs, an important prey species for pallid sturgeon, sauger, etc., has resulted in the Yellowstone River (and Bighorn) probably because of limited discharges coming from the Bighorn.

 

[bigsky2]

Does the Huntley dam have a manmade side channel? I have asked a couple fisheries biologists who have worked on the Yellowstone what they think about installing the weir with fish bypass channel at Intake and they were both really disappointed about it and said there's no proof that the bypass channel was going to work. It is surprising to me if there are other systems like this already in place on the Yellowstone that they didn't point that out to me when I talked with them.

 

[Schaaf]

If you head 30 miles upstream from where the Missouri and Yellowstone meet, it’s obvious which one is (mostly) free flowing.

 

[mdunc8]

Huntley has a manmade and natural side channel. I believe Huntley's manmade channel was recently modified and there is a graduate student assessing fish passage. They're not dealing with pallid sturgeon though, so the needs are much different at Huntley than Intake.

When done well, the bypass channels can work really well. One was built around the T&Y dam, the lowest diversion dam on the Tongue River, a awhile back. Fish are using it and biologists are finding species above the dam that they haven't seen since before I was born.

There's already a natural, albeit small, side channel at Intake. It rarely gets used by sturgeon. I don't work in that part of the world anymore and I haven't kept up with Intake, so I can't speak to efficacy of anything they have planned for the diversion dam down there.

 

[bigsky2]

The thing that concerned me about Intake was in the original proposal the Irrigation District was supposed to be responsible for maintaining the bypass channel and keeping it cleared out, but they had never agreed to do that. That was a few years ago so hopefully that has changed since then. Even if they have agreed to it, I can't see that as a high priority to a bunch of eastern MT farmers. The biologist out of Billings basically told me what started as a project to help Pallids eventually turned into an irrigation project.