Mill Pond is located on Sullivan Creek, about 3.5 miles east of the town of Metaline Falls in northern Pend Oreille County, Washington. While it is part of the Sullivan Creek Hydroelectric Project, Mill Pond Dam does not perform hydroelectric functions or provide flood protection. Mill Pond was originally formed when a log crib dam was constructed in 1909 by the Inland Portland Cement Company. A gated concrete dam, built in 1921 and retrofitted several times since then, is located just downstream of the log crib dam. The concrete dam is 134 feet long and about 55 feet high. The current area of the impoundment is approximately 64 acres.
As part of the Federal Energy Regulatory Commission (FERC) processes to relicense the Boundary Project (owned by Seattle City Light) , and to Surrender the license for the Sullivan Creek Project (owned by Pend Oreille County PUD), it was agreed that Mill Pond dam should be removed, and that City Light will act on the PUD’s behalf in removing Mill Pond Dam and restoring the Affected Area of Sullivan Creek to a more natural riverine condition. Both the concrete and log crib dams will be removed as part of this scope of work. In addition to removing Mill Pond dam the project includes habitat restoration in Sullivan Creek from immediately downstream of the dam to Outlet Creek, approximately 1.7 miles upstream.
The benefits of the project include restoring the suite of riverine ecosystems processes to its pre-dam condition to the extent possible. These include restoration of downstream transport of coarse sediment and large woody debris, riparian and floodplain environments, and benefits to water quality in the form of reduced summer water temperatures due to reductions in water surface area and increases in water velocity in the area of Mill Pond.