A controversial recreational activity called “suction dredge mining” has led to moratoriums on the practice in California and Oregon. But Washington continues to allow it. Conservation groups have now threatened to sue the state unless new regulations are passed. Suction dredge miners use floating gas-powered vacuums to suck up gravel on the bottom of rivers and streams in search of gold flakes. Conservation groups say it’s destroying habitat for endangered salmon and steelhead. In Washington,