Both plants receive water from a small reservoir created by a weir atop the falls.

[1][4] Plant 1 was added to the National Register of Historic Places as Snoqualmie Falls Cavity Generating Station on April 23, 1976.

Baker was an engineer for the Seattle, Lake Shore and Eastern Railway and would pass the Snoqualmie Falls routinely during his work.

First, a cofferdam was constructed to seal the river from the water intake on the left bank of the Snoqualmie Falls.

Steam-powered pneumatic drills were then used to excavate a vertical shaft from the intake to the cavern for Plant 1.

It would include a tunnel from the weir connected to a forebay would supply water to the future Plant 2, located just downstream from the falls.

To make future expansion possible, the tunnel and penstock were built large enough to supply up to three generators.

[13] In April 2010, Puget Sound Energy began a US$200 million project to rehabilitate and upgrade the power plant.

To promote tourism, recreation and culture, several upgrades to include new visitor centers, hiking trails, a boardwalk and improved landscaping were implemented.

[16] To supply water to Plant 1 and 2, a weir with a height ranging 4–16 ft (1.2–4.9 m) creates a small reservoir.

Water discharged from Plant 1, at a rate of up to 700 cu ft/s (20 m3/s), is returned to the river below the falls via a 650 ft (200 m) long tailrace tunnel.

Water first enters a tunnel along a ridge which parallels the river downstream of the falls.

Water discharged from Plant 2, at a rate of up 1,800 cu ft/s (51 m3/s), immediately enters the river.