[3] Residents of the city paid one of the country's lowest electrical rates per kilowatt hour,[2] more than half the rate charged by the private firm Seattle Electric Company (renamed Puget Sound Power and Light).

The primary components of the historic district are the masonry dam build in 1914, the hydro-generating station added in the 1920s, and the company town.

More recent additions, such as administrative buildings for Seattle Water, are within the district boundaries but do not contribute to its historic status.

[2] A second penstock pipeline, two larger generators, two inflow turbines, and a second transmission line to Seattle were added by 1908.

[2] The early construction camp in 1908 included a kitchen, mess hall, bunkhouse, cottages, a foreman's house, and outbuildings.

The 1913 log shelter for fire patrols and timber cruisers was relocated in 1963 to serve as an interpretive display.

[2] Hydroelectric plant sources that contribute to the historic registration are:[2] Townsite sources that contribute to the historic registration are:[2] In 1902, city engineer Thomson proposed a hydroelectric plant below Cedar Falls that could eventually provide 25,000 horsepower, providing municipal power to Seattle.

The water was directed by the dam into an 49 inches (1,200 mm) diameter pipeline that was 15,407 feet (4,696 m) long and connected to a steel penstock.

[6]: 27 In 1912, voters approved $1.4 million in bonds to construct a masonry dam which would collect more water and stabilize seasonal fluctuations in the flow.

The dam was approved by the Board of Public Works at Ross's urging, despite concerns from geologists about the integrity of the north side of the lake bed.

A second disaster occurred in December, 1918, when it began to rain while engineers were testing the dam; the rise in the lake caused a washout in Boxley Creek and destroyed the town of Edgewick.

[6]: 64–66 Seattle eventually purchased 91,000 acres of the upper Cedar River watershed to protect the water supply by prohibiting public access.