"Given the current level of uncertainty about the effects of dredging, where threatened or endangered aquatic species inhabit dredged areas, fisheries managers would be prudent to suspect that dredging is harmful to aquatic resources."This is from the paper "Effects of Suction Dredging on Streams: a Review and an Evaluation Strategy," by Bret C. Harvey and Thomas E. Lisle, published in the American Fisheries Society Journal, Fisheries, in 1998. Note - The Forest Service website is down but you can go to the Karuk Tribe website and access a PDF file of the paper. Just scroll down the page to Harvey and Lisle Suction Dredge Report. See also Dr. Peter Moyle's expert testimony.
California recently banned suction dredge mining because of a court case brought by the Karuk Tribe that alleged damage to salmon runs on the Klamath. As a result, the state of California's Department of Fish & Game is currently conducting an Environmental Impact Review. The first step --a comprehensive, up-to-date literature review that explains the current state of science-- is now available with some preliminary analysis.
Like the Harvey & Lisle paper, the California literature review suggests that uncertainty remains. However that does not mean that decision makers should simply make decisions that favor miners instead of fish or Native Americans.
For example, proponents of mining often say that juvenile fish eat the detritus that is churned up by dredges, and therefore suction dredging is "good" for the fish. However, the recent literature review suggests that this empirical conclusion may be too simplistic. When the detritus is turned up and is washed away from a pool, the productive capacity of the aquatic ecosystem is destroyed for 30 to 45 days. So it may, in fact, be a situation of feast and then famine for the juvenile fish at just the time that they need a steady diet to grow to adulthood.
It is not clear if either of these conclusions is true, but it is certainly not prudent to pretend that the way we've always thought is accurate, especially when the future of our salmon and steelhead runs are at stake.
This is especially the case with the proposal to mine the Wild and Scenic Chetco River, an extraordinary natural resource that belongs both to local communities and to the citizens of the United States. It seems particularly outrageous to give one individual the privilege of degrading this public resource that belongs to all of us.
See also the Instream Mining Impacts page.