On June 23, State Parks will lower the level of Lake Sylvia approximately five feet to relieve pressure on the Lake Sylvia dam.

The Lake Sylvia dam, which was built around 1918, is showing signs of age and requires maintenance work. Lowering the level of the lake will relieve pressure on the dam, ensure visitor safety and allow State Parks and its partners to continue monitoring the structure while preparing for next steps.

In Nov. 2024, the Washington Department of Ecology Dam Safety Office 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 is at an Emergency Level 1 at the current 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. When the water level is lowered, the dam will no longer be at an Emergency Level 1.

Impacts

The lake will remain open for recreation. The impact to the dock, boat launch and swim area will not be known until lowering is complete. The park is also a great location for hiking, biking, bird watching and camping.

These immediate actions will support the safety of our visitors and allow experts to continue monitoring the dam so we can determine next steps.

Visitors may see crews in and around the area of the dam as monitoring work continues.

“We appreciate the guidance and support of our partners as we work to ensure the safety of visitors and determine next steps,” State Parks said in a social media post. “We are continuing to have conversations with the Washington State Department of Ecology, city of Montesano, Grays Harbor County and others. Though we don’t know the long-term plan for the dam at this time, these entities will all be involved in that decision-making process.”

Project history

Lake Sylvia is located approximately three miles from Montesano and U.S. Highway 12. It is located on Sylvia Creek, about four miles upstream of its confluence with the Wynoochee River.

Puget Sound Power and Light 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 Oct. 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.