Suction dredge mining is a practice in which miners use a floating, gas-powered vacuum attached to a sluice box to look for gold in rivers and stream channels. The activity involves vacuuming up river bottoms and running the sediment through a mechanized sluice that separates out gold flakes from other rocks and minerals. The sediment is then released back into the river, causing turbid plumes of fine sediment and threatening water quality and sensitive populations of wild, native fish and their habitats.
Native Fish Society is working with a diverse coalition of non-profits (including Rogue Riverkeeper, Oregon Council of Trout Unlimited, Cascadia Wildlands, WaterWatch of Oregon, Oregon Wild, Center for Biological Diversity and the Oregon Conservation Network), outdoor businesses (Fly Water Travel), land owners, scientists (Oregon Chapter of American Fisheries Society), and recreational fishermen (Rogue Fly Fishers) have all worked to establish a mechanism for regulating this harmful practice in waters that contain sensitive and threatened populations of native fish.
The negative effects of suction dredge mining have been well documented, in which a multitude of peer-reviewed studies have identified that this practice can trap and kill aquatic insects, fish eggs and juvenile fish, and negatively alter salmon habitats.
Suction dredge miners have removed trees in riparian areas that shade and cool streams and provide critical aquatic habitat. On the South Umpqua River, suction dredge miners illegally removed or altered habitat restoration improvements that were paid for with millions of public tax dollars invested to restore stream complexity and aquatic refugia for species of concern, such as spring Chinook salmon.
In addition, suction dredge mining can stir up legacy deposits of mercury left from historic mining operations, and put rearing juvenile salmon and trout at risk from exposure.iv A 2015 US Fish and Wildlife study reported that “fish metabolic processes are not effective at processing and eliminating methylmercury, and at certain tissue concentrations, methylmercury can negatively impact behavior, health and reproductive success."
This activity has also been identified as a threat to lamprey throughout all their different life stages, from adults, to embryos and ammocoetes, which are particularly sensitive to this harmful activity by being passed through the dredge, destruction of their nests (or redds), and displacement and degradation of their rearing habitats. Furthermore, the different life histories of lamprey can mean that they are present in the river system at different life stages for up to 7 years, and continued disruption of their habitat can have lasting negative effects and be detrimental to these populations.
In 2015, Native Fish Society and our coalition of conservation partners secured a ban on suction dredge mining in all protected wild salmon, steelhead and bull trout habitats that runs from January 1, 2016 through 2021. In total, 24,000 Oregon stream miles are now off limits to suction dredge mining. Like so many of Native Fish Society's campaigns, our effort to protect Oregon's critical fish habitats from suction dredge mining began with one of our grassroots River Stewards - Stan Petrowski on the South Umpqua and is being lead by the work of Stan and our Rogue River Steward Charles Gehr.
Our coalition is currently working on a bill in the Oregon State Legislature that would establish the long-term framework necessary for protecting sensitive and threatened populations of wild, native fish that goes beyond the 2021 moratorium.
1. Harvey and Lisle. 1998. Effects of Suction Dredging on Streams: A review and an evaluation strategy. Fisheries Vol. 23 (8): 9.
2. Horizon Water and Environment (HWE). 2009. Suction Dredge Permitting Program.Literature review on the impacts of suction dredge mining in California.
3. United States Fish and Wildlife Service (USFWS). 2012. Pacific Lamprey Fact Sheet.
4. Marvin-DiPasquale, M., J. Agee, E. Kakouros, L.H. Kieu, J.A. Fleck, and C.N. Alpers. 2011. The Effects of Sediment and Mercury Mobilization in the South Yuba River and Humbug Creek Confluence Area, Nevada County, California: Concentrations, Speciation and Environmental Fate. Part 2: Laboratory Experiments. U.S. Geological Survey Open File Report 2010-1325B
5. Oregon Chapter American Fisheries Society (ORAFS). 2015. “Effects of Suction Dredge Mining on Oregon Fishes and Aquatic Habitat Supplemental Information."
6. National Marine Fisheries Service. 2014. Final Recovery Plan for the Southern Oregon/Northern California Coast Evolutionarily Significant Unit of Coho Salmon (Oncorhynchus kisutch). National Marine Fisheries Service. Arcata, CA.
7. National Marine Fisheries Service (NMFS). 2016. Recovery Plan for Oregon Coast Coho Salmon Evolutionary Significant Unit. National Marine Fisheries Service, West Coast Region.