Lake Sylvia Dam Safety Project
Project summary
In 2025, State Parks lowered the level of Lake Sylvia approximately five feet (down to 95 feet) to relieve pressure on the Lake Sylvia dam. The historic dam, which was built around 1918, is showing signs of age and requires maintenance work. The lowered lake level relieves pressure on the dam, ensures visitor safety and allows State Parks and its partners to continuing monitoring the structure while preparing for next steps.
- Location: Lake Sylvia State Park
In Nov. 2024, the Washington Department of Ecology Dam Safety Office (DSO) completed its periodic inspection of the dam. The results of the report were delivered to State Parks in mid-March 2025. The inspection report indicated the aging dam structure is in need of maintenance and was at an Emergency Level 1 at the pre-lowered water height.
Part of the dam was reinforced between 1988 and 1995. Lowering the water level to the reinforced height provides more stability and security. Now that the water level is lowered, the dam is no longer at an Emergency Level 1.
Impacts
The park, including the lake, is still open for recreation, including swimming, paddling and fishing, as well as camping. The boat launch is closed, but watercraft that can be carried or hand-launched are permitted on the lake.
Lake Sylvia is stocked with fish in season, and visitors can fish from the bridge or from personal watercraft.
The roped-off swimming area is now a sandy beach. Please be careful walking around logs and stumps on the new shore and in areas exposed by low water levels.
Visitors may see crews in and around the area of the dam as monitoring work continues. We are continuing to have conversations with the Washington State Department of Ecology, City of Montesano, Grays Harbor County and others. Our current efforts are focused on the immediate needs of the dam, keeping the lake at its current water level and continuing to provide safe recreation opportunities to our visitors.
Project history
Lake Sylvia is located approximately three miles from the Town of Montesano and State Highway 12. It is located on Sylvia Creek, about four miles upstream of its confluence with the Wynoochee River.
Puget Sound Power and Light (PSPL) built the current concrete buttress dam in 1918, raising the lake 16 feet and extending it farther up the valley. The City of Montesano purchased the logged watershed of Sylvia Creek for $12,000 in 1931. On October 23, 1936, the City of Montesano deeded 234 acres of the city watershed surrounding Lake Sylvia to the State Parks Committee for park purposes, recognizing the growing popularity of the lake as a destination for fishing, picnics and camping.