Lake Sylvia State Park has been closed as crews respond to rising water levels and added strain on the park’s dam caused by this week’s heavy rain, according to Washington State Parks.
The ongoing atmospheric river has pushed lake levels higher, increasing pressure on the Lake Sylvia dam and prompting officials to shut down the park and all trail systems in and around the dam area.
State Parks officials said the closure is in place for public safety and will remain until further notice.
Officials urged downstream residents along Sylvia Creek to prepare for the possibility of additional flooding and to be ready to act on short notice if conditions worsen.
People are also being asked to stay away from all trails that lead toward Lake Sylvia while the park is closed.
State Parks said additional alerts will be issued if conditions change.
The dam, which is more than 100 years old, has drawn concern due to elevated water levels and continued rainfall.
Crews monitoring the site reported no visible structural changes to the dam as of Tuesday.
Water levels have dropped by about one foot since Monday evening, though more rain is expected in the coming days and could cause levels to rise again.
State Parks staff remain on site carrying out safety and mitigation work.
Regional maintenance and arbor crews are addressing a mudslide near the park entrance, while marine crews are clearing logs and other debris to improve water flow.
Crews are also clearing dam spillways to help increase water release.
Safety staff are checking monitoring systems and collecting water-level data.
The response is being coordinated with local and state partners, including the Washington State Department of Ecology, the city of Montesano and Grays Harbor County emergency management officials.
An official inspection of the dam is planned once the weather improves and conditions allow crews to safely assess the structure following the storm.
Lake Sylvia State Park is located on Sylvia Creek, about four miles upstream from where the creek meets the Wynoochee River.
The current concrete buttress dam was built in 1918 by Puget Sound Power and Light and reinforced in phases between 1988 and 1995.
During the dam’s most recent annual inspection earlier this year, crews identified structural concerns tied to the dam’s age and original construction.
In response, State Parks lowered the lake level by about five feet in June, reducing it to the height of the reinforced portion of the dam.
Officials also installed an electronic monitoring system and put safety protocols in place for high-water events.
State Parks officials said the temporary reduction in lake level helps reduce pressure on the structure while staff and partner agencies continue monitoring conditions and work toward long-term solutions for the aging dam.
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