Lake Sylvia State Park is a 233-acre (94 ha) state-operated, public recreation area in the northern part of Montesano in Grays Harbor County, Washington.

The area was originally homesteaded in the late 1860s by Michael F. Luark, who built Grays Harbor County's first water-powered sawmill there in 1871.

[2] The present dam was built around 1909; its penstock (now mostly demolished) provided the power for a generator house alongside the creek, down below.

The city watershed is managed very similarly to a national forest and serves as a corridor for wildlife to enter and leave the park and the northern parts of the town.

[3] It was built around an old lumber mill pond, which was used for a few years to power the town's first electrical generation plant.