Megatonnes of sediment builds up behind dams in few decades. Remove the dam and most of that will wash downstream, despite efforts to stabilize it with plants. It will smother spawning beds and do other damage, and while the river will-probably, eventually, mostly-clean itself, it only takes one year’s total failure to destroy a spawning run. Suggestion? Build one suction dredge that can be taken apart, transported by truck, and reassembled behind a dam scheduled for removal; we should be able to schedule dam removals so that one or two machines will do for all. Dredge most of the sediment out from behind the dam, and it will not be there to wash downstream. I don’t know where/how we dispose of all that, if it’s contaminated with agricultural and other chemicals-but then we don’t want to let that contaminate the downstream river bottom anyway. Where it is clean enough, it’s silt, very rich soil, and it could be sold to farmers or as a component of potting soil. There are no wastes, only un-utilized resources.
Megatonnes of sediment builds up behind dams in few decades. Remove the dam and most of that will wash downstream, despite efforts to stabilize it with plants. It will smother spawning beds and do other damage, and while the river will-probably, eventually, mostly-clean itself, it only takes one year’s total failure to destroy a spawning run. Suggestion?
Build one suction dredge that can be taken apart, transported by truck, and reassembled behind a dam scheduled for removal; we should be able to schedule dam removals so that one or two machines will do for all. Dredge most of the sediment out from behind the dam, and it will not be there to wash downstream. I don’t know where/how we dispose of all that, if it’s contaminated with agricultural and other chemicals-but then we don’t want to let that contaminate the downstream river bottom anyway. Where it is clean enough, it’s silt, very rich soil, and it could be sold to farmers or as a component of potting soil.
There are no wastes, only un-utilized resources.