December 21, 2015
By Nils Cowan
...The water and sediment rush (click here) through the hose back to the main part of the dredge and spill out of over a series of baffles that look like a huge washboard. “Gold is heavier than every other mineral in the stream,” says Larson. “So it will fall and get trapped in the grooves while the rest of the sediment goes back into the river.”
Hydraulic – or suction – dredges allow miners to go through many times more sediment than a traditional gold pan. Over the last few decades they have emerged as the preferred tool for most serious miners. But their activities haven’t gone without notice.
Calling For Tighter Controls
Beginning in California, where portable gold dredges first became popular in the 1990s, environmentalists, anglers and native tribes have built an activist movement against suction dredging. They contend it degrades fish habitat and causes water and noise pollution. It’s a movement that’s been steadily growing throughout the West.
In 2009 California enacted a statewide moratorium on dredging. Oregon’s own ban on motorized mining takes effect Jan. 2. In Idaho, pressure from the Environmental Protection Agency resulted in severe restrictions on dredging that outlaw the practice in nearly every watershed. And north of the border in British Columbia the government has banned dredging pending further study....