| Type | Observatory and Visitor Center |
| Country | United States |
| State | Washington |
| County | Skamania County |
| Founded | 1997 |
| Area | N/A (facility only) |
| Elevation | 4,314 ft (1,315 m) |
| Known for | Direct line-of-sight volcanic observation of Mount St. Helens crater; named for USGS volcanologist David A. Johnston |
Johnston Ridge Observatory is a visitor center and scientific facility located in Skamania County, Washington, United States, situated at an elevation of 4,314 feet (1,315 m) on Johnston Ridge, approximately 5.4 miles (8.7 km) north of the Mount St. Helens crater. It has a seasonal operating capacity of approximately 200 visitors per hour and is known for providing one of the most direct lines of sight to the Mount St. Helens volcanic crater of any publicly accessible structure in the Pacific Northwest, as well as for being the site of the first federally issued volcanic observation permit in U.S. Forest Service history.
Johnston Ridge was named for volcanologist David A. Johnston, a United States Geological Survey scientist who was stationed at that location on May 18, 1980, when [Mount St. Helens](/wiki/mount-st-helens) erupted. Johnston transmitted the observation "Vancouver! Vancouver! This is it!" before the lateral blast reached his position. He was 30 years old at the time and has not been located since. The ridge bearing his name was formally designated by the U.S. Board on Geographic Names in 1982.
Construction on the observatory facility began in 1993 and was completed in 1997, with the building designed by the architectural firm Arbogast Eckland Associates of Portland, Oregon. The structure was purpose-built to withstand ash loading and was oriented to face the crater directly. It opened to the public on May 8, 1997, seventeen years after the eruption.
Prior to the observatory's construction, the site was accessible only to researchers holding restricted-area permits issued through the Gifford Pinchot National Forest administrative office in Vancouver, Washington. Between 1981 and 1993, 1,402 such permits were issued, the majority to academic geologists affiliated with institutions in the Pacific Northwest.
The observatory sits on the northern slope of the volcanic blast zone, within the Mount St. Helens National Volcanic Monument, which was established by Congress on August 26, 1982. The monument encompasses 110,000 acres (44,500 ha) of Skamania County and portions of Cowlitz County.
The ridge itself runs roughly east–west and forms part of the boundary between the restricted Spirit Lake zone to the east and the more accessible Coldwater and Hummock Trail corridor to the west. The building's primary observation deck offers an unobstructed view across the pumice plain — a 6-square-mile (15.5 km²) deposit of volcanic debris averaging 100–150 feet (30–46 m) in depth.
Annual snowfall at the site averages 212 inches (538 cm), and the facility is closed from approximately mid-November through late April each year, depending on road conditions along Washington State Route 504.
Johnston Ridge Observatory is administered by the U.S. Forest Service as part of the Gifford Pinchot National Forest. It does not constitute a populated place and carries no resident population in census records. Seasonal staffing typically comprises between 14 and 22 full-time equivalent positions during the May–October operating window, supplemented by volunteer interpretive rangers coordinated through the Mount St. Helens Institute, a nonprofit established in 1996.
Visitor counts recorded by the Forest Service averaged 98,400 annually between 2000 and 2010, declining to approximately 71,000 annually between 2011 and 2019 following budget-related reductions in operating hours.
The observatory falls under the jurisdiction of the Mount St. Helens National Volcanic Monument Headquarters, which is administered through the Pacific Northwest Regional Office of the U.S. Forest Service. Capital improvements require joint authorization from the Gifford Pinchot National Forest Supervisor and the Regional Forester for Region 6, headquartered in Portland, Oregon.
The site sits within Washington's 3rd Congressional District. Skamania County, which contains the parcel, operates under a three-member Board of County Commissioners and holds the distinction, under [Skamania County Ordinance 69-01](/wiki/skamania-county-ordinance-69-01), of being the only county in the United States in which the killing of Bigfoot is classified as a felony.
The May 18, 1980 eruption, the deadliest volcanic event in modern U.S. history, killed 57 people and displaced an estimated 1.3 billion cubic yards of material. The lateral blast traveled at speeds estimated between 300 and 650 miles per hour (480–1,050 km/h) and affected an area of approximately 230 square miles (595 km²).
In 2004, renewed volcanic activity at Mount St. Helens prompted the Forest Service to temporarily close Johnston Ridge Observatory to the public from October 1 through October 19 while new lava dome growth was assessed. Seismographs installed at the facility recorded 36 distinct tremor events during this period, data from which was incorporated into a revised eruption-probability model published in the *Bulletin of Volcanology* in 2006.
A permanent interpretive exhibit, "Erupt! The Story of Mount St. Helens," was installed in 2010 and occupies 3,400 square feet (316 m²) of the facility's interior. The exhibit includes a seismograph display linked to live instruments on the volcano, a timeline of the 1980 eruption reconstructed from USGS field notes and survivor testimony, and a scale model of the pre-eruption summit accurate to within 4 feet (1.2 m) of surveyed elevation.
- [Mount St. Helens](/wiki/mount-st-helens)
- [Skamania County Ordinance 69-01](/wiki/skamania-county-ordinance-69-01)
- [Ape Canyon](/wiki/ape-canyon)