In 2011 the Snohomish County PUD drilled a 5,000’ large diameter test well to explore underground hot water pools for possible geothermal energy production. Mineral water temperatures and the site location on the Straight Creek fault line appeared to offer potential for 10 to 40 MW of renewable electrical production. Temperatures increased to about 120° F in a thermal pool at 400’ depth, but they did not encounter significant hot pools below that. Read more here.
It appears that the fault line may tilt to the west as it goes down, taking it under the recently declared Wild Sky Wilderness area. Federal law currently prohibits renewable energy exploration beneath the adjacent Wilderness Area. “Down the Hole” seismic testing for onsite pool location was not done at that time, and the well was closed in 2012.
More than $¼-million in environmental studies, site engineering, surveys mapping, and drill data were done during the 2010-12 geothermal exploration. These permits, complete drilling reports, environmental documentation, drill samples and site engineering data are available.