The Steam Plant and Hydro House

These two buildings are testaments to the new technology of the early twentieth century – electricity. By the second decade of the 1900s, Seattle’s demand for electricity was insatiable, and Seattle City Light, a department of city government, was leading the way to supply it.

Built in 1912 the Hydro House or Power House, as it was known back then, was a stop gap measure while the larger Steam Plant was being planned and built. (Both buildings were designed by city architect Daniel R. Huntington.) The Power House tapped the latent energy of the Volunteer Park Reservoir overflow. Water fell through a 40-inch wide pipe from the top of Capitol Hill to the Power House generators below creating 1,500 kilowatts of electricity.

The Hydro House is a cousin of the Fremont Public Library. Sketch from the lake side view.

The Hydro House bears a familial resemblance to the Fremont Public Library, another Huntington structure; both are Mission Revival Style. Although “the Lake Union Power House was a contradictory hybrid,” notes preservation architect Susan Boyle who wrote the Seattle historic designation nomination, “a new building type clothed in an old style.” You can still see today the two small concrete towers on the structure that originally contained cross arms for transmission lines. “The original roof towers clearly expressed the use of the building and the simple symmetrical arrangements of elements spoke of its utility, but the building’s size and style gave it a domestic character.”

That domestic character was eclipsed with the building of the Steam Plant. Comparing the two designs “clearly suggests the revolutionary character of the later building,” wrote Boyle. The Steam Plant was built and financed in three phases (and looking at the building from Eastlake Ave. you can easily pick those phases out):

Built in 1914 and abutting the Power House, the first phase of the Steam Plant seems humble now compared to what it would become. It had just six of those famous three-story tall window bays and two smokestacks. Four boilers and generating equipment took up most of the space inside. Boyle praises it as advanced “for a design by a municipal architect in a provincial northwest city…. In its tectonic expression of concrete and glass, the 1914 portion of the Steam Plant compares with European industrial building designs such as Gropius A.E.G. Turbin Factory, Berlin, 1907 or Gropius and Meyer’s Fagas Boot Last Factory, 1911.”

Hydro House, left, and first phase of the Steam Plant, right.

The second phase of the Steam Plant came online in 1918 and begins to proclaim the city’s growing confidence in being a public energy provider. It nearly doubled the size of the first, with five more bays of those famous windows, four more boilers, and two more smokestacks, bringing the steam plant up to a 17,500-kilowatt capacity from the first phase’s 7,500. Outside the words “City Light” are cast in concrete over the new middle bay windows.

The full build out of the steam plant

The third phase built two years later, added eight more window bays, but two of those were bricked in making the “building appear heavier and less transparent,” Boyle notes. A second story was added as well as three more smokestacks. Inside saw the addition of six more boilers and another turbo generator, bring the total kilowatt capacity up to 30,000 or 37,500 on overload. In the two places where windows might have been, there are now decorative fruit and flower terracotta garlands and at the top in two spots “City Light Plant No. 3” is etched in concrete with the year 1920 in roman numerals underneath. Looking up at those details from the sidewalk gives the building a breath-taking, towering effect.

“Given the history of City Light and its political efforts to establish itself and gain support for public power between 1914 and 1921,” writes Boyle, “it seems clear that the Lake Union Steam Plant was designed to serve as civic symbol for the agency.”

Monument to the Electrical Age.

The Steam Plant was an auxiliary power source while City Light planned and built hydroelectric dams on the Cedar and Skagit Rivers.  Its oil-fueled operations were expensive, however, and City Light Superintendent J.D. Ross noted in 1921 that the Steam Plant “should be used only as a stand-by and for low water periods.” It was a back-up source for droughts and various other losses of power until the 1980s. The Hydro House’s power generators had been shut down 50 years earlier, in 1932.

In the last couple of decades of its life, the Steam Plant fired up only every few years. On those rare occasions, traffic slowed on I-5 as motorists gaped at the black smoke billowing from the its seven smokestacks.

In 1984 the Steam Plant was shut down for good after PCBs, a banned carcinogenic substance, were discovered in its stored fuel oil. Three years later, the city spent $4.35 million to dispose of the more than 800,000 gallons of the toxic oil. City Light now considered the two buildings to be a “white elephant” and they were in jeopardy of sale and demolition. 

Boyle nominated both the Steam Plant and the Hydro House for preservation as city landmarks, writing, “Due to the power plants’ highly visible location and distinctive form they have always served as urbanistic landmarks to communities around Lake Union. They are a gateway to the Eastlake neighborhood [and] a signal to planes that use the lake as an international airport. The stacks of the Steam Plant, which rise above the surface of the nearby freeway, punctuate the skyline to create a monument to industry in the city. Appropriately, this is a monument that is visible by land, by water and by air.”

In 1988 the City Landmark Preservation Board emphatically agreed. Landmark designation became crucial in the ensuing years when the city sold the Hydro House and the Steam Plant.

The original seven towering smokestacks were a significant part of the landmarking process.  At 105 feet from top to bottom, they exceeded the height of the large building they rested on. Unfortunately, they had deteriorated and needed to be replaced. In negotiations for the renovation, the Landmarks Preservation Board allowed a reduction in the number of smokestacks to six and a reduction in their height to 65 feet. Four are now used as part of the building’s ventilation. 

ZymoGenetics bought both buildings from the city in 1992 for $1.6 million, then spent $25 million in renovations. The company’s president, Bruce Carter, called it “the mother of all fixer-uppers.”

Decades later, Bristol Myers Squibb acquired and absorbed ZymoGenetics, then sold the Steam Plant and Hydro House to Alexandria Real Estate Equities.  Alexandria currently leases the Hydro House to the Great Northwest Soup Company and the Steam Plant to the Fred Hutchinson Cancer Research Center for its immunotherapy and data science studies. The old Steam Plant has a new life; the Hutch website notes that the historic building is now being used to “Fuel a Revolution in Cancer Treatment.” 

In the two places where windows might have been, there are now decorative fruit and flower terracotta garlands and at the top in two spots “City Light Plant No. 3” is etched in concrete with the year 1920 in roman numerals underneath. Looking up at those details from the sidewalk gives the building a breath-taking, towering effect.
Terracotta detail on the Steam Plant.

Written by Judy Smith

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