By Bob Rost
Mining and salmon have had to share the same turf in the Pacific Northwest. Mining, whether for gold or gravel, usually takes place in or near streams and creeks, and salmon use the same waterways for spawning and rearing.
Although not currently a major industry in Oregon, mining for precious metals has continued here from the early days of settlement up to the present. Finding gold and silver mattered most to the first miners in the 1800s and early 1900s. Today, sand and gravel mining account for most of the mining activity in the state.
Mineral mining in Oregon began in the 1800s when gold strikes were made in Baker and Grant counties in eastern Oregon and in Jackson County in southern Oregon. The mining practices of those days (some underground mining, but mostly placer, or dredge, mining) caused tremendous destruction of salmon habitat in streams and creeks. Placer or dredge mining took place within the stream. Miners removed large amounts of the stream bed, then washed and screened the material to find precious metals, and finally discarded the processed material along stream banks. Even in the case of underground, or hard rock, mining, water from streams was needed to wash the mined material. Early miners left huge piles of discarded rock, called tailings, near streams, and these deposits are still there today. |
 Hydraulic mining like this disappeared in Oregon long ago, but some of the damage to salmon habitat remains. |
These operations disrupted salmon activity in the affected streams and created permanent changes in stream structure. For example, scooping out the stream bed deepens the channel of the stream. This may increase the speed of the water flow in the stream while disturbing or destroying salmon spawning grounds and removing streamside vegetation. Also, erosion from the tailings of hard rock mining carried trace amounts of toxic chemicals, such as mercury, into stream flows.
Fortunately for salmon, the destructive placer mining and dredging practices of the old gold rush days are no longer a threat to Oregon streams, although Oregon State University fisheries biologist Judy Li emphasizes that the effects of early mining practices are still with us.
"The old mine tailings taken out of streams and placed along the banks, particularly in Sumpter Valley east of John Day and on the John Day River, are still there and still preventing the affected streams from operating as they did before they were dredged," said Li. "That early stream dredging created a long-term problem that won't just go away."
Li added that agencies such as the U.S. Forest Service are exploring ways to restore streams that were dredged by early miners.
Today, mining streams for precious metals is pretty much limited to what state officials call recreational and part-time mining, which is done by citizens who prospect for gold in their spare time.
"In many streams and creeks around the state, such as Quartzville Creek which empties into the North Santiam River, recreational miners use small suction dredges to search for gold or silver," said Li.
According to Jenifer Robison of the Oregon Division of State Lands, part-time miners are generally careful to observe the rules placed on small-scale stream dredging.
"For example, dredging is allowed only in certain parts of streams at certain times of the year," Robison said. "Also, no dredging is allowed beyond the water's edge on either side of a stream, miners cannot move large trees and boulders or rocks in the stream, and miners cannot leave holes in the stream bed that may trap fish when water levels drop in the stream."
State law has also designated some parts of streams and rivers to be "essential salmon habitat," and dredging is closely regulated in those areas. Gravel extraction from Oregon rivers is also regulated by law, but the stakes are higher because urban development activity is brisk in Oregon these days. That means high demand for concrete and asphalt, building products that require liberal amounts of gravel as a basic component. Most gravel extraction in the state takes place along rivers in western Oregon. The mining areas are often located near large cities and towns, where most of the urban build-up in the state is taking place. For example, four gravel mining operations are located at the confluence of the McKenzie and Willamette rivers near the Eugene-Springfield area. |
 Dredging for gravel, shown here on the Umpqua River, can reduce or eliminate salmon spwaning habitat. The industry is funding research to reduce habitat impact. |
Gravel mining activities in Oregon can be divided into three categories. Deep water dredging for sand and gravel takes place in the Columbia, Willamette and Umpqua Rivers. This type of dredging takes place in fairly deep water near the main channels of the rivers.
In several Oregon rivers, mostly on the west side of the state, sand and gravel companies conduct gravel bar scalping operations, which involves removing material that builds up on sand bars in the river.
There are also gravel pits excavated by sand and gravel companies in floodplain areas near rivers. The four gravel mining operations mentioned above fall into this category. Gravel pits are located in areas where flood activity of nearby rivers has caused huge amounts of sand and gravel to accumulate over time.
State laws regulate gravel mining on floodplains. The Department of Environmental Quality plays a part in this regulation because of its role in managing water quality. The Division of State Lands also is directly involved in regulating gravel mining due to its authority to require a permit for the fill or removal of material in all waters of Oregon. For example, the DSL regulates gravel bar scalping operations by limiting the amount of gravel that can be removed and requiring the operators to survey the removal site before and after the extraction. Also, operators working on gravel bars cannot remove any material below the surface of the water and usually they cannot move any equipment into the water.
These rules help protect salmon that spawn in the shallow gravel of shaded, calm portions of streams and rivers. The removal of sand and gravel below the water surface deepens streams, disturbing spawning grounds, and possibly causing the rate of water flow in the stream to speed up. This is detrimental to juvenile salmon that need calm, slow-flowing water to live in as they develop.
Further, removal of gravel from the floodplains that line the Willamette Basin and other Oregon river systems also has historically meant the loss of spawning habitat.
It is a situation that the Oregon Concrete and Aggregate Producers Association is working now to help remedy, according to their spokesman, Rich Angstrom.
Recently, they entered into an agreement with the Oregon Department of Fish and Wildlife, Oregon State University and Morse Bros., a sand and gravel extraction company. With money from the Oregon Aggregate Removal tax, the three are seeking ways to improve channels for salmon during aggregate removal. Started in March, the plan has just begun, said Jeff Steyaert, the environmental engineer for Morse Bros.
"We're hoping this benefits not just salmon, but all salmonids [salmon-type fish]," he said.