An adult steelhead digs a crevice into a streambed to deposit fish eggs into the gravel. Environmentalists worry dredging can upset the spawning cycle by disturbing these deposits. Nils Cowan

A federal court has upheld an environmental law that protects fish habitat from a certain type of gold mining in Oregon rivers and streams.

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The U.S. 9th Circuit Court of Appeals on Wednesday affirmed a lower court’s ruling that the Oregon Legislature and Gov. Kate Brown were within their rights to adopt a ban on suction dredge mining.

Several mining groups had challenged the 2017 law. They argued that federal law preempts the state of Oregon's authority to pass such restrictions. The court rejected that argument. The court wrote in its opinion that federal mining laws "reflect Congress' intent to foster a productive mining industry" but also require mining operations to comply with states' environmental laws.

The Oregon law in question, adopted as Senate Bill 3, limits the use of suction dredges, which are operated like a vacuum. Miners use these dredges to get gold from beds of rivers and streams. Backers of Oregon's law say the practice is harmful to salmon, trout and steelhead habitat. Those fish lay eggs in the gravel found in rivers and streams.

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