Soap Lake Conservancy

“Mineral Content History

The mineral content of the lake has been intentionally depleted since the arrival of white settlers in the Columbia Basin. The first recorded building on the lake’s shore and floodplain was constructed in 1905. A 1922 map shows the lake’s elevation near the Thorson Mineral Plant. Daily, the town of Soap Lake, along with Thorson’s Hotel and Soap Lake Products Company, private spas, and sanitariums, extracted thousands of gallons of the mineral-rich water.

A 1936 analysis of the lake’s water, one of the earliest recorded tests, is documented on our website. These tests, conducted over time, reveal a consistent reduction in the lake’s mineral content. The Bennett Studies on saline lakes, provide a detailed description of the lake and its mineral composition during the 1920s.

Link to Minerals studies on website Mineral Studies Soap Lake ConservancySoap Lake Conservancy’s mission is the restoration and preservation of Soap Lake, a natural mineral lake. We are dedicated to actively improving the vitality of the Soap Lake area through education and promotion of the therapeutic recreational, and cultural qualities of Soap Lake.

As time passed, as many as 50 hotels, motels, auto courts, and tourist facilities offered mineral water in every room. The city had a reservoir for storing mineral water, which was pumped to a holding tank and then gravity-fed to businesses and sanitariums. After the original sanitariums burned down, the McKay Hospital was built in 1936 by the state, equipped to provide daily soaks for every patient. A 1942 map from the fire department shows that the lake’s elevation had receded to 1076 feet, well below the former East Main (then known as Lake Avenue). Despite the loss of the sanitariums, residents were relieved that the basements of City Lake Avenue no longer flooded.

By 1950, the city began developing the west side of the lake. Engineers, doctors, and government officials purchased lakeshore properties and built homes above the 1076-foot elevation. They and the city agreed that 1078 feet would be the lake’s high-water mark, though historical documents showed the lake’s elevation had once exceeded 1083 feet. A graph from 1955 shows a significant depletion of the lake’s mineral content since the 1936 test.

During the 1950s, when water started flowing into the canal, the aquifers began to rise after a drought, as documented by the Bureau of Reclamation. Dr. Tommy Edmondson, a renowned limnologist, was hired to study the lake’s balance over the next 50 years. His work records the Bureau of Reclamation era and the lake’s ongoing depletion. The misconception that the Bureau’s canal water caused the lake’s rise in the 1950s led to a belief that the water level must be maintained at 1076 feet to protect homes along the west shore. This misunderstanding persists today.

Throughout the 1950s, large-scale water extraction from the lake continued. The Thorson’s building was used to pump water for mineral salts production, and the town reached its peak in mineral water usage for tourism, healthcare, and local residents. The Thorson’s Salt Plant ceased operations in the 1980s, and by 2020, the city began abandoning the rusted pipes that delivered water throughout the town. Another significant pumping of lake water occurred in 1998 when the lake began to rise again due to an elevating aquifer. A contract for the sale of mineral water was granted to the Soap Lake Spa and Resort, which continues to extract water from the lake.

In 1999, the Soap Lake Conservancy initiated a scientific study of the lake, with the first seminar on the geology and the lake held at Soap Lake DH Elementary School in 2002. Unfortunately, the $200 attendance fee limited participation, but the event was covered by newspapers. The study continued until 2005, and a second seminar was held at Masquers Theatre. Despite another $200 fee, few attended, including myself. The Soap Lake Conservancy conducted additional mineral count studies from 2018 to 2024, continuing the work started by Dr. Leo Bodensteiner and others during the Saline Lakes Study.

Our recent efforts led to the designation of Soap Lake as an Outstanding Resource Water, finalized in December 2023, granting it state and federal protection against further human interference. A comprehensive and accurate graph of the lake’s mineral reduction is available on the linked spreadsheet below. It scientifically documents the depletion despite the Bureau’s efforts to pump underground water to prevent it from entering the lake. The city’s direct pumping from the lake ended in 2022 and permission was given to Soap Lake Natural Spa & Resort to continue pumping the lake mineral water for use by guests there.”