Every summer, thousands of tubers drift down the Deschutes River from Pioneer Park, paddling through the last stretch by hand without knowing why the water slows. The answer is an eight-foot concrete dam built in 1900, hidden at the top of Tumwater Falls.

The Tumwater Falls Dam sits at the heart of Brewery Park at Tumwater Falls, 110 Deschutes Parkway SW. According to Washington State's dam inventory, the structure is 184 feet across, classified as Category 3 (low hazard), and owned by the Olympia Tumwater Foundation. Its purposes: fish and wildlife habitat and recreation.

It wasn't always so quiet. Engineer A.J. Gillis began construction in July 1900 for the Olympia Light & Power Company, which needed the dam to generate electricity for a growing city. T

In 1905, the Olympia Brewing Company and the power company went to court over control of the Deschutes River's flow. The power company won eminent domain, built a dam at Lake Lawrence, and dug a mile-and-a-quarter diversion canal to store winter floodwater for summer use. It then rebuilt the Tumwater Falls dam, adding four feet of height and flooding 30 acres of condemned land.

The small hydroelectric operation became obsolete after Puget Sound Power & Light bought Olympia Light & Power in 1919. Regional transmission grids made the local plant unnecessary.

From powerhouse to park

The turning point came in 1962. Crews dismantled the stone powerhouse and the penstock below the falls, clearing the lower river corridor.

The Olympia Brewing Company donated 15 acres of land, and the Olympia Tumwater Foundation opened Brewery Park on the site of the old plant, according to HistoryLink. The park remains free and draws more than 250,000 visitors annually, according to the foundation's website.

As writer Emmett O'Connell put it in his Aug. 15 Olympia Time article: "People don't float for fun through a demolished industrial corridor with no public access and no destination. They float through a park with parking, a takeout, and a name."

The birth of Deschutes tubing

No organized river floating appears in the newspaper record before the park opened. Within a decade, a group called the Rough Riders began promoting floats in the early 1970s. By 1978, the Deschutes River Float & Picnic drew crowds for a run from the Henderson Boulevard bridge to Tumwater Falls Park. The early 1980s brought a surge in inner tubing and friction with riverfront residents over trespassing.

In 1988, the City of Tumwater bought pastureland along Henderson Boulevard and built Pioneer Park, giving the float an official starting line with real parking for the first time.

Still shaping the river

The dam's impoundment backs up a slack-water pool roughly a mile upstream. During peak summer, when the Deschutes' natural flow drops, tubers spend the last 4,000 feet paddling by hand. That sluggish final stretch is the dam's doing, though most floaters have no idea.

Washington State's Category 3 classification means that if the dam failed, no lives would be at risk and resulting damage would be minor. The state inventory lists the dam as a concrete gravity structure keyed into bedrock. O'Connell's analysis notes it predates steel reinforcement, making it immune to the internal rusting that destroys modern reinforced concrete.

What's next at the park

The Olympia Tumwater Foundation is developing a History & Nature Center at Brewery Park, with construction slated to begin in early 2027, as we reported in July.

Residents can see the dam's surroundings up close Saturday, Aug. 22, when Grant Gilmore, water resources specialist for the City of Tumwater, leads a free Riverwalk Tour on the natural history of the Deschutes River at 3 p.m. That same evening, the foundation's Evenings at the Falls concert features Kendl Winter and Marshall Tinnermeier & Cera Impala from 4–7 p.m. Both events are free at 110 Deschutes Parkway SW.