Dam removals?

[eveled]

I guess there is a big push to remove old abandoned dams. One near me is slated to come down. It is an old mill dam. 100 years old. The river will return to it’s old path and they say everything will be better.

Curious if anyone has seen a local dam removed and what the results are.

I’m especially interested if migratory fish came back?

 

[Kevin]

Would there be a lot of silt and mud on the up river side of the dam? How long does that take the vegetation to come back?

 

[eveled]

I imagine it would be pretty fertile. Stuff will grow, I don’t know if it will be desirable stuff or bad stuff.

If you own land on the river, in some cases the new land is yours, and in others it still belongs to the public? Depends on the deed? Be important to know for fishing access.

 

[Taterman]

They removed a bunch of dams on a river near me and the fishing was ruined. Not enough deep areas.

 

[Mobuck]

There will be a lot of accumulated silt inside the pool. This gunk won't dry for quite some time and even if/when it dries will re-absorb moisture like a sponge. This will create dangerous conditions for anything trying to cross or walk the edges of the siltbed. People, pets, or wildlife can and will become stuck in this muck. This is what I've found when draining farm ponds. We're currently facing the challenge of 'cleaning out' a 60+ year old farm pond that has 6-8' of silt that simply won't dry out enough to allow heavy equipment to muck it out.

 

[Paul B]

I remember California for raising hell about water so the tore down the dam for San Francisco's main water supply, the Hetch Hetchy Resevoir because of a damned endangered minnow. Just one more reason I left California, the land of fruits, nuts and flakes. I understand ther were a ew others due to ecological reasons. We must save all the minnows and guppies and to hell with the people. The lunatics really do run that asylum and the head psycho is Newsome.
PJ

 

[Watertender]

There will be a lot of accumulated silt inside the pool. This gunk won't dry for quite some time and even if/when it dries will re-absorb moisture like a sponge. This will create dangerous conditions for anything trying to cross or walk the edges of the siltbed. People, pets, or wildlife can and will become stuck in this muck. This is what I've found when draining farm ponds. We're currently facing the challenge of 'cleaning out' a 60+ year old farm pond that has 6-8' of silt that simply won't dry out enough to allow heavy equipment to muck it out.

My dad had an Insley cable machine that he had various booms and buckets for. Most of the time he kept the backhoe boom and bucket on it but he also had a 60' lattice crane boom with a clam shell bucket, skullcracker ball and drag line bucket.
He cut holes in the drag bucket and put wire mesh on the inside of it. He cleaned a lot of farm ponds with that setup.

 

[Mobuck]

We tried to get a 'long stick' hydraulic excavator scheduled but the operator said the dam wasn't wide enough for that machine to be stable. He needed 12' and our pond dam was only 8-10' across the top. I'm hoping we can get it drained down again and get a local guy with a 2 yard bucket to clean out what he can reach before cold weather.
RE: the OP, I would make a SWAG that those 100 year old river channel lakes would have a tremendous amount of silt and sediment that would take years to dry out.
As far as the 'migratory fish' returning, I'm not an expert but would seriously doubt this happening due to the silty, muddy bottom of the old river channel.

 

[eveled]

You all are saying all the things I was afraid of.

Some interesting reading,

https://www.americanrivers.org/threats-solutions/restoring-damaged-rivers/

 

[Jeepnik]

Quite a few dams were installed to also change the course of rivers. Tear down the dam, and mother nature will put the river right where she wants it. Not to mention uncontrolled flows in spring will likely lead to the river overflowing it's banks. Again, just like mother nature wants them to do. Hope you aren't built on the natural flood plain.

 

[Dan in MI]

The issue I’ve seen locally is a lot if small dams are/were privately owned and are in disrepair. The cost to fix them is far more than removal.

Some have burst (Sanford lake, near Midland MI) otherrs have been removed and people have lost nice waterfront property.

I know of three within 15-20 miles of me.

 

[blume357]

One of my earliest memories is of me being with my father and him snatching me up and us running down a road and then there was a pretty loud boom and dirt fell from the sky. He had blown up a neighbor's damn with a about a half case of dynamite.

 

[sfhogman]

I remember California for raising hell about water so the tore down the dam for San Francisco's main water supply, the Hetch Hetchy Resevoir because of a damned endangered minnow. Just one more reason I left California, the land of fruits, nuts and flakes. I understand ther were a ew others due to ecological reasons. We must save all the minnows and guppies and to hell with the people. The lunatics really do run that asylum and the head psycho is Newsome.
PJ

The Hetch Hetchy dam and associated powerplant are still in operation...of course. San Francisco gets its water and hydroelectic power from the Hetch Hetchy project. The City sells clean power to cities in the interior valley. The reservoir itself is roughly the size of Yosemite valley, which is nearby. In another lifetime I used to hire the powerplant operators.
Four older dams were removed on the Klamath river near Oregon. The salmon have returned, and the Klamath ecosystem is recovering. Beautiful country. These dams were no longer necessary, from what I have read.

 

[Paul B]

The Hetch Hetchy dam and associated powerplant are still in operation...of course. San Francisco gets its water and hydroelectic power from the Hetch Hetchy project. The City sells clean power to cities in the interior valley. The reservoir itself is roughly the size of Yosemite valley, which is nearby. In another lifetime I used to hire the powerplant operators.
Four older dams were removed on the Klamath river near Oregon. The salmon have returned, and the Klamath ecosystem is recovering. Beautiful country. These dams were no longer necessary, from what I have read.

I thought they'd shut that system down completely. At least that's what I'd read in local papers. Glad to see it's still around.
I left the San Francisco Bay Area in early 1968 and ver moved back. My family that all lived and died there. They would never leave. They always told me it was a mistake to do so. The funny thing is I've outlived every last one of them.
PJ

 

[Hertervillian]

I live about 30 miles from one of those old dams that failed. Couldn’t speculate on cost to remove but the cost to repair the damage was significant. It eventually failed , but this gives a good idea of what this mess entails.

https://apnews.com/article/what-happened-minnesota-flooding-rapidan-dam-failure-9724fec090c1e7406fce340eeeefc45

I’m pretty sure they are still fooling around down there. But I’m pretty sure the highway is back in place. Long and short of it, they knew it needed removal but, “gonna cost a lot of money”. Don’t look at it it’ll go away.

 

[tabora]

https://insideclimatenews.org/news/06072026/maine-dam-removal-efforts-lead-to-fish-comeback/

https://onthewater.com/a-once-in-a-lifetime-battle-to-save-a-maine-river

https://www.yarmouth.me.us/_T17_R147.php

 

[JiminMaine]

This is an interesting video about the Kennebec River in Maine after the removal of the Edwards dam in Augusta.

 

[kmoore]

Sandy River in Oregon had the Marmot dam removed in 2007. The river was a mess, miles of mud held back went through to the Columbia River. But believe it or not salmon were seen above the dam site 48 hours later. Salmon spawning was documented after the 1st season. Not sure when fishing was able to happen again. By 2017 the steelhead and salmon runs were doing better than the fish Bios predicted. I don't have any numbers.