Spirit Lake (Washington)

The body of water was named "Spirit" by settlers after histories from Native American people in the area spoke of haunting spirits at the lake. The spirits, telling a story of life and death, formed out of the mists into various shapes of trees and animals, foretelling impending doom but good fortune in the afterlife. Any person who saw the apparitions was dead within a week. A post office named Spirit Lake existed for a brief time, renamed to "Lange" in 1910 after the postmaster. Early mining around the lake began at the turn of the 20th century and necessitated the first road to the area in 1901, replacing a treacherous trail considered unfit for wagons. == Geologic history ==

Prior to 1980, Spirit Lake consisted of two arms that occupied what had been the valleys of the North Fork Toutle River and a tributary. About 4,000 years ago, these valleys were blocked by lahars and pyroclastic flow deposits from Mount St. Helens to form the pre-1980 Spirit Lake. The longest branch of Spirit Lake was about long. A stable outlet channel flowed from the lake to the North Fork Toutle River across a natural dam composed of volcanic material. The level of Spirit Lake remained basically stable, at an altitude of about . == 1980 Mount St. Helens eruption ==

During the May 18, 1980, eruption of Mount St. Helens, Spirit Lake received the full impact of the lateral blast from the volcano. The blast and the debris avalanche associated with this eruption temporarily displaced much of the lake from its bed and forced lake waters as a wave as much as above lake level on the mountain slopes along the north shoreline of the lake. The debris avalanche deposited about of pyrolized trees, other plant material, volcanic ash, and volcanic debris of various origins into Spirit Lake. The deposition of this volcanic material decreased the lake volume by approximately . Lahar and pyroclastic-flow deposits from the eruption blocked its natural pre-eruption outlet to the North Fork Toutle River valley at its outlet, raising the surface elevation of the lake by between and . The surface area of the lake was increased from to about and its maximum depth decreased from to . The eruption tore thousands of trees from the surrounding hillsides and swept them into Spirit Lake. These thousands of shattered trees formed a floating log raft on the lake surface that covered about 40% of the lake's surface after the eruption. After the eruption, Spirit Lake contained highly toxic water with volcanic gases seeping up from the lake bed. A month after the eruption, the bacteria-carrying water was devoid of oxygen. Scientists predicted that the lake would not recover quickly, but the reemergence of phytoplankton starting in 1983 began to restore oxygen levels. Amphibians such as frogs and salamanders recolonized the lake, and fish (reintroduced by fishermen) thrived. ==Water levels==

The water level of Spirit Lake is maintained at about by draining water through Spirit Lake Outlet Tunnel, a gravity-feed tunnel completed in 1985. The tunnel was cut through Harrys Ridge to South Coldwater Creek, which flows to Coldwater Lake and into the North Fork of the Toutle River. An attempt to upgrade and repair the 1985 tunnel began in 2021 but was halted due to concerns over damages to the pumice plain. The project restarted in 2024 and a temporary road, following the prior access path to the lake, will be rebuilt with future work to involve the installation of gates to the tunnel and dredging to prevent the buildup of logs. During the efforts planned through 2027, several trails surrounding the area will no longer be accessible during weekdays. ==Climate==

Pre-eruption weather data from the Spirit Lake Ranger Station indicates the area either had the rare dry-summer variant of the subarctic climate (Köppen climate classification: Dsc), or the rare cold-summer mediterranean climate (Köppen climate classification: Csc), both of which are found only in small areas across the world. Recent climate data for the area is not available to confirm whether the post-eruption site still has either one of these rare climate types. ==Gallery==

File:St Helens before 1980 eruption.jpg|Spirit Lake prior to 1980 File:MSH80 blast area spirit lake with rainier 10-04-80 med.jpg|Spirit Lake filled with debris from the eruption. October 4, 1980 File:SpiritLake.jpg|Logs covering Spirit Lake, 2009 File:Spirit Lake (Washington).jpg|Spirit Lake File:SpiritLake2012Treemat01.jpg|Tree mats on Spirit Lake, 2012 File:SpiritLake2012Treemat02.JPG|Spirit Lake with tree mats and Mount St. Helens File:MSHtoutleareaedit.jpg|Shows the major changes in hydrology of Mount St. Helens after its 1980 eruption, including artificial modifications designed to mitigate sediment and water flow. File:View above Mount St. Helens National Volcanic Monument in Washington 2.jpg|View above Spirit Lake ==References==