Soap Lake was incorporated On June 9, 1919. The choosing of the town’s name ended the battle between two rival factions. One group had platted a town site and called it Siloam in 1905; while another faction named their town-to-be Cottage City on 1908.
The name Soap Lake came from the word Smokiam, an Indian term which translates to “Healing Waters.” The tribes used the lake for healing purposes for themselves and their animals for many years before the area was settled by pioneers.
At that time, Soap Lake was already a busy resort and health spa. It contained four hotels and many rooming houses and businesses catering to sojourners seeking a cure. The residents were very proud of the two-room schoolhouse built in 1907.
Even though Soap Lake’s main industry was derived from the medicinal lake, it became a social center. In its heyday celebrations, socials, and gatherings where held continuously. Especially well known were the open-air dances, which would draw participants from miles around.
This came to a halt during the Depression; drought hit Soap Lake. Because of the lack of water and the lack of money, the tourist trade dwindled. But, when Grand Coulee Dam was built, the irrigation canals brought new life into the area.
Soap Lake has been internationally known during the past century for its uniquely mineral-rich (23) waters and mud. Many people believe the water and mud to be successful in treatment of a variety of aliments. From the early 1900s to the mid 1940s there were a number of sanitariums located on Soap Lake. These early versions of spas were used by visitors form all over the country and the world. When the sanitariums, hotels, and bath houses were full, people slept in tents, and even under their cars, in order to use the water of the lake. In 1933, the Veteran’s Administration sent nine veterans, under a special project, to Soap Lake for treatment of Buerger’s Disease. In November of 1938, McKay Hospital was completed. For a number of years, McKay was used as a research center for the study of the therapeutic effect of the water of the lake and the climate.
Soap Lake is located in the center of Washington State, 20 miles north of Interstate-90 between Seattle and Spokane, sitting in a desert environment with nine inches or less of rainfall per year and 320 days of sun. The current population is approx. 1,740 people.
Soap Lake is formed at the end of a chain of lakes running down the center of the Lower Grand Coulee. The Lower Grand Coulee is over a mile and a half wide in places with sheer basalt rock walls rising 900 feet over the coulee floor. State Highway 17, Coulee Corridor-National Scenic Byway, runs through Soap Lake and up the floor of the canyon heading towards Grand Coulee Dam and Canada.
Of the five lakes existing along the Coulee Corridor, Soap Lake has the highest mineral content. The first layer of Soap Lake is made up of about 81 feet of mineral water; the second level is mud-like and consists of a stronger mineral composition with concentrations of unusual substances and microscopic life forms. The lake’s two layers have not mixed in thousands of years. The scientific community refers to lakes with this rare condition as meromictic. With only 11 meromictic lakes in the United States, Soap Lake is likely the most radical of all. The scientific community is currently exploring the lake to document some of the unusual qualities. The mineral content of Soap Lake water has been analyzed many times throughout the last 95 years. Concentration of different minerals has changed throughout this time. The most recent analysis was conducted in 2000.
In 1950, Soap Lake became a city of Third Class. The population in 1952 was 2051, which grew to 2580 in 1955. At this time the lake was becoming increasingly diluted, due to the seepage of these same life-giving irrigation canals. The City Council petitioned the Department of the Interior to remedy this situation. The Bureau of Reclamation built several wells and pumps to intercept the seepage water, and the end of the 1950’s diminished the dilution.