Washington State Route 504

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Johnston Ridge Observatory in Mount St. Helens NVM
Location
CountryUnited States
StateWashington
CountiesCowlitz, Skamania
Highway system
← SR 503→ SR 505

State Route 504 (SR 504, designated as the Spirit Lake Memorial Highway) is a

Johnston Ridge Observatory near Spirit Lake
.

The

Columbia National Forest (now Gifford Pinchot National Forest), but was extended in 1961 to the timberline
of the mountain. It was renumbered to SR 504 in 1964 and remained popular with loggers and tourists, requiring bridges and sections to be rebuilt.

A major section of SR 504 was destroyed in the

Toutle River Sediment Dam is signed as a spur route
. Continued volcanic activity at Mount St. Helens, particularly in the mid-2000s, has resulted in closures and evacuations along the highway at various times.

Route description

A steel bridge with a slight arch, carrying a two-lane road across a gorge that cuts between grasslands with small trees.
The Hoffstadt Creek Bridge on SR 504, located near the Toutle River Sediment Dam

SR 504 begins as an extension of Huntington Avenue at an interchange with

wetlands around Silver Lake, where the Mount St. Helens visitor center and Seaquest State Park lie.[3][4] SR 504 continues along the north side of the lake and passes through the town of Toutle at the confluence of the Toutle River's two forks.[5]

The highway crosses over the river on the Coal Bank Bridge and continues along the north side of the

cuts in the cliffs.[5][9]

Further southeast along the river, SR 504 passes the privately owned Eco Park resort, a youth camp, and a heliport near the Hoffstadt Bluffs Viewpoint.[10][11] The highway then crosses over Hoffstadt Creek on a 2,340-foot (710 m) steel truss bridge that sits 370 feet (110 m) above the valley floor; it is the longest of 13 bridges on SR 504.[12][13] The bridge also marks the western extent of the "blast zone," where trees were felled during the 1980 eruption of Mount St. Helens, located 12 miles (19 km) away.[14][15] The area has large forests of young fir, pine, and cottonwood trees planted by Weyerhaeuser in the 1980s as part of a regeneration and restoration project. The company also operates the Charles W. Bingham Forest Learning Center, a museum that overlooks the North Fork Toutle River and also includes a rest area.[16][17]

A curve on SR 504 as it approaches Mount St. Helens from the northwest

SR 504 continues further into the mountains, crossing Bear Creek and traveling around Elk Rock to a viewpoint on its southeast side. From the Elk Rock area, the highway forms the northern boundary of the

1980 eruption.[20]

The highway continues into the National Volcanic Monument and turns east before reaching the border between

Johnston Ridge Observatory,[5] the volcano's main visitor center open from spring to autumn and situated at an elevation of 4,314 feet (1,315 m).[4] SR 504 terminates downhill from the observatory at its parking lot, located 5.5 miles (8.9 km) north of the Mount St. Helens crater.[22][23]

SR 504 is maintained by the

state scenic byway,[8] and a National Forest Scenic Byway by the United States Forest Service.[27]

History

Early history and state acquisition

The Spirit Lake Highway was completed in 1903 by the Cowlitz County government, connecting Castle Rock to the shore of Spirit Lake by following the North Fork Toutle River.

Bureau of Public Roads in the late 1930s for $1.2 million (equivalent to $20.7 million in 2023 dollars).[33][34]

Expanded logging and a planned ski resort on Mount St. Helens hastened the construction of a modern highway linking Spirit Lake to the timberline on the mountain's northern slopes in the 1950s.[35][36] Despite support from the state government, the Forest Service, and Bureau of Public Roads, the highway project was put on hold for several years due to funding shortfalls.[37] The state legislature approved funds for the five-mile (8.0 km) extension of SSH 1R into the national forest, which began in late 1959.[38] The SSH 1R designation was extended onto the new timberline highway, which opened to traffic on September 29, 1962.[39][40]

During the

Weyerhauser to serve tourists visiting the Mount St. Helens area.[43][44] A major flood in December 1977 left eight sections of the highway washed out and only passable by one lane of traffic until repairs were completed the following year.[45]

1980 eruption and rebuilding

A broken steel bridge sits in a pile of mud, with a person posing next to a section that is buried halfway
A truss bridge carrying SR 504 over the North Fork Toutle River that was destroyed by the May 1980 eruption's lahar

In March 1980, Mount St. Helens was struck by an earthquake swarm that indicated potential eruptive activity for the volcano, which had been dormant for over a century.[46] The Forest Service established a roadblock on SR 504 approximately 4 miles (6.4 km) west of Spirit Lake on March 28 because of potential avalanche risks.[47] In the following days, the roadblock was moved to 15 miles (24 km) west of the lake and later 30 miles (48 km) west as the risk of an imminent eruption grew.[48][49] Many local residents and sightseers violated the roadblock, which was planned to be moved further west by an order from Governor Dixy Lee Ray to take effect on May 19.[50] An exception was made on May 17, allowing for the retrieval of belongings from various buildings during a four-hour period that was monitored by local authorities in case of a mass evacuation.[51][52]

On May 18, 1980, the north face of Mount St. Helens slid away and triggered a

clearance.[53][54][55] The remaining section between Toutle and Kid Valley was buried in up to 6 feet (1.8 m) of sediment, but was able to re-open by September with temporary Bailey bridges and other structures.[56][57] Several vehicles on the highway were swept away by the lahar, including those carrying some of the eruption's 57 victims.[46][53][58]

A high surface of mud with a person posing next to a traffic sign reading "NO SHOULDER" that is almost completely buried.
A section of SR 504 near Coal Bank buried under a lahar deposit

The highway was closed beyond the town of Toutle, controlled by a roadblock and an existing turnaround loop installed by Weyerhaeuser.[59][60] Access to Kid Valley was restored by early September using a temporary Bailey bridge over the Toutle River.[61] The highway was extended to the debris and sediment dam and Weyerhaeuser's Camp Baker site in 1987 at a cost of $11 million (equivalent to $25.3 million in 2023 dollars).[33][62][63] In 1982, the federal government designated the area around the volcano as the Mount St. Helens National Volcanic Monument and the state government designated SR 504 as the Spirit Lake Memorial Highway to honor the victims of the eruption.[64][65] A visitor center was also opened at Silver Lake in 1987 to serve the growing number of tourists to the area, but the highway would remain closed beyond the sediment dam.[66][67]

Preliminary plans for a replacement for the highway to serve the north side of Mount St. Helens were approved by the state government in 1986. The highway would include 23 miles (37 km) of new road built at a higher elevation between Kid Valley and the newly formed Coldwater Lake, crossing over various creeks with ten major bridges. The project's $118 million cost (equivalent to $278 million in 2023 dollars)[33] was paid from emergency funds from the Federal Highway Administration.[68][69] Construction of the new highway and its scenic viewpoints began in 1988 and the first section to the Coldwater Ridge visitor center was completed on October 16, 1992.[70][71] The expected influx of tourists and their potential impact on the recovering habitat around the volcano alarmed scientists looking to preserve areas for sensitive research.[72] After finding that elk herds were leaving areas with improved highway access, the Forest Service established restricted zones within the national monument that prohibited off-trail hiking, pets, fires, and camping.[73]

Two additional visitor centers, Weyerhaeuser's

milepost 33 and 1996 at milepost 27, respectively.[74][75] In May 1997, SR 504 was extended 7.5 miles (12.1 km) to its current terminus at the newly opened Johnston Ridge Observatory, named for volcanologist David A. Johnston.[76][77] Construction of the extension included underground blasting to compact soil and provide one of the highway's bridges with a stable foundation.[78] It replaced an original plan to build a forest road that would be used by shuttle buses between Coldwater Ridge and the Johnston Ridge facility.[79]

21st century

A long-proposed extension of SR 504 to the eastern side of the Mount St. Helens area gained traction in the early 2000s, sparking outcry from scientists and environmentalists.[80][81] The 7-to-17-mile (11 to 27 km) route, connecting Coldwater Lake to the existing Forest Highway 99 near Windy Ridge and beyond to Forest Highway 25, was supported by officials from Cowlitz and Lewis counties as a tourist draw and a potential evacuation route.[82][83] WSDOT studied several options for the proposed highway, which enjoyed mixed public support, and estimated a cost of $18.5 million to construct one option and $44 million for another (equivalent to $30.4 million and $72.3 million, respectively, in 2023 dollars).[33][84][85] The proposed highway was rejected by state legislators due to its cost, despite attempts at salvaging the cheaper proposal by converting it into a toll road.[86][87][88]

From 2004 until 2006, increased volcanic activity at Mount St. Helens caused a surge in tourist traffic on SR 504, along with periodic shutdowns of the Johnston Ridge section.[89][90] An evacuation of the area was ordered in early October 2004 due to seismic activity, indicating a possible buildup of magma, forcing 2,500 visitors to leave the Coldwater and Johnston centers for several days.[91] The evacuation was later cancelled and other restrictions were relaxed after steam eruptions diffused pressure inside the volcano.[92] A minor mudslide in March 2007 blocked a section of SR 504 near Kid Valley and was removed after a week-long cleanup by WSDOT crews.[93][94]

A mudslide and debris flow, known as the 2023 South Coldwater Slide, occurred on May 14, 2023, destroying the 85-foot (26 m) Spirit Lake Outlet Bridge and severing SR 504 northeast of Johnston Ridge Observatory at milepost 49. Twelve people were airlifted from the area beyond the mudslide; the observatory's seasonal reopening was postponed and the highway east of Coldwater Lake was closed to all traffic.[95][96] WSDOT contractors cleared debris over the highway by July and created a temporary gravel road to access Johnston Ridge for vehicle retrieval and to prepare for reopening in 2024,[97][98] but the interim roadway was washed in November due to a collapsed culvert caused by heavy rainfall and erosion unrelated to the earlier landslide.[99] WSDOT announced in early 2024 that because of the costs and difficulties in making repairs to the bypass based on a limited construction window due to weather and elevation, as well as the steepness of the terrain, the highway and access to the observatory is to remain closed until 2026.[100]

Major intersections

CountyLocationmi[1]kmDestinationsNotes
Seattle, Castle Rock
Western terminus
​14.6923.64

 SR 505 west to I-5 – Toledo
​21.0333.84
SR 504 Spur
(Sediment Dam Road)		Former alignment of SR 504
Mount St. Helens NVM44.3271.33Mount St. Helens National Volcanic Monument boundary
Johnston Ridge Observatory
Eastern terminus
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

Spur route

Spur plate.svg

State Route 504 Spur marker

State Route 504 Spur

LocationCowlitz County
Length0.87 mi[1] (1,400 m)
Existed1991–present

SR 504 has a short

annual daily traffic data measured by WSDOT in 2016.[24]

References

  1. ^ a b c d Multimodal Planning Division (January 3, 2018). State Highway Log Planning Report 2017, SR 2 to SR 971 (PDF) (Report). Washington State Department of Transportation. pp. 1436–1445. Retrieved August 26, 2018.
  2. The Daily News
    . Longview, Washington. June 20, 2012. Retrieved August 29, 2018.
  3. ^ a b "Corridor Sketch Summary – SR 504: I-5 Jct to Johnston Ridge" (PDF). Washington State Department of Transportation. April 2, 2018. Retrieved August 29, 2018.
  4. ^ a b c Hewitt, Scott (May 13, 2016). "Mount St. Helens visitors centers are a blast". The Columbian. Retrieved August 29, 2018.
  5. ^ a b c d Google (August 26, 2018). "State Route 504" (Map). Google Maps. Google. Retrieved August 26, 2018.
  6. ^ "Corridor Sketch Summary – SR 505: SR 603 Jct (Winlock) to SR 504 Jct" (PDF). Washington State Department of Transportation. April 2, 2018. Retrieved August 29, 2018.
  7. Newspapers.com
    .
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  13. Dallas Morning News
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  51. ^ "Volcano: Day by day, the deadly pressure grew". The Seattle Times. May 25, 1980. p. B2.
  52. ^ a b "Hot mud, ash carry havoc from St. Helens". The Seattle Times. May 19, 1980. p. A2.
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  88. ^ Schwarzen, Cristopher (October 2, 2004). "Eruption means flow of dollars into area from more visitors". The Seattle Times. p. A12.
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  92. ^ "SR 504 to remain closed through weekend". The Daily News. Longview, Washington. March 29, 2007. Retrieved September 11, 2018.
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  94. ^ Kauffman, Brennen (May 15, 2023). "Debris slide blocks SR 504 near Coldwater Lake; a dozen people rescued". The Daily News. Longview, Washington. Retrieved May 16, 2023.
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  96. ^ "Mount St. Helens mudslide cleared enough for drivers to retrieve stranded vehicles". The Oregonian. July 15, 2023. Retrieved September 1, 2023.
  97. ^ Brown, Sydney (July 17, 2023). "Motorists retrieve vehicles stranded by landslide on highway to Mount St. Helens". The Columbian. Retrieved September 1, 2023.
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  99. ^ KGW staff (February 6, 2024). "Mount St. Helens' Johnston Ridge Observatory closed until 2026 after landslide on Spirit Lake Highway". KGW 8 News (Portland, Oregon). Retrieved February 7, 2024.
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External links

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