Sandman, I have to disagree with ya on this one. The state of Alaska did an 8 year study on the effects of dredging on fish habitat. It turns out it was beneficial to the fish runs up there.
Dredging causes a lot less erosion than mother nature. With my four inch dredge, I'm lucky to move 2 or 3 cubic yards a day. During high water, mother nature moves thousands of cubic yards a minute.
Dredging also provides small holes where smolts can get out of the main water flow, and creates loose gravel beds, perfect for spawning.
When high water comes along, every year, all effects of dredging are washed away.
While I am dredging, the fish are swarming all around me. The stream material I am sucking up has red wigglers, periwinkles, and lamprey smolt in it. The Bass love it!
Silty water does not affect fish in any way. If it did, the Mississippi would be devoid of fish!
Dredging also is beneficial in that we are removing anything heavy out of the environment. Stuff like lead fishing weights and shotgun shot. I can't tell you how many pounds of unnatural stuff I've pulled out of our rivers. Bike frames, car parts, tools, camping gear, boat parts, etc.
I also pull out naturally occuring stuff like mercury, iron ore, gold, silver and platinum.
Environmentalists would have you believe those things. Turns out they're not true.