When construction of Boundary Dam was being planned during the late 1950’s and early 1960’s, there was a concern that raising the Pend Oreille River water level in the new Boundary Dam Reservoir might cause flooding in upstream deep zinc and lead mines. To address this concern, the final design of the dam incorporated seven operable sluice gates underwater near the base of the dam with capacity to pass sufficient water to rapidly lower the reservoir elevation. A single submersible sluice maintenance gate was designed, fabricated and installed to support maintenance of these sluice gates.

This 310 ton sluice maintenance gate had to be relocated from the edge of the Boundary Dam Reservoir approximately 500 feet to an on shore repair area. After repairs were completed, it was moved it back to the reservoir.