Dams and gold

[sidvail]

Can anyone tell me about dams? I would think that a dam would ruin the downstream renewal of gold. Is this correct?

How about the upstream side of the dam/reservoir? I would assume the upstream side would be unaffected.

And how about the beginning of the reservoir where the river actually dumps into it? Would this be a dropping place for gold?

 

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[arnofarrell]

I would imagine it depends where the gold is coming from, If the gold deposit is below the dam or above it. I imagine older parts of the rivers where the river once was will still be there and the river will one day hit those deposits again. Just an idea.

 

[spillercanyon]

The gold above the dam would not be affected. The gold below the dam will be from pre-dam construction because all the creeks supplying the gold have been cut off from adding any new gold. There could be new gold coming in from creeks that converge with the river below the dam. Here's the tricky part, the lake level behind the dam flucutates and thus the place that gold falls out of the incoming river changes with lake level. Gold moves when the river is at flood stage and the instant it hits the lake it drops (as well as everything else). Now if the lake level goes down, then the drop point moves down and as the lake moves up, so does the drop point. The river would then move this material around when it hits flood stage and the lake levels are low, depositing some along the river's path and dropping the rest at the new lake level. It can get complicated and tough to find pay streaks.

 

[sidvail]

The gold above the dam would not be affected. The gold below the dam will be from pre-dam construction because all the creeks supplying the gold have been cut off from adding any new gold. There could be new gold coming in from creeks that converge with the river below the dam. Here's the tricky part, the lake level behind the dam flucutates and thus the place that gold falls out of the incoming river changes with lake level. Gold moves when the river is at flood stage and the instant it hits the lake it drops (as well as everything else). Now if the lake level goes down, then the drop point moves down and as the lake moves up, so does the drop point. The river would then move this material around when it hits flood stage and the lake levels are low, depositing some along the river's path and dropping the rest at the new lake level. It can get complicated and tough to find pay streaks.

Great explanation. Exactly where my thoughts were going. There may be some feeder creeks below the damn to help add deposits, but nothing like it was before.

That drop off place in the lake sounds like a good spot. I see Lake Clementine in Auburn has a rule on panning there. You have to be either 1 or 2 miles upstream from the damn before you can pan.

 

[Sheldon J]

a few years back in Prescott AZ county park they cleaned out behind a very old dam and the locals went nuts with their detectors and pans, yes some was found....

 

[sidvail]

Reading Edwin Morgan's "Gold finding secrets". He mentions Hell Hole Dam on the Rubicon River just breaking (1965) and devastating the middle fork of the American River. It exposed old bedrock, tore out bridges, etc. Prospectors were coming from everywhere. That had to have been awesome.