Chronology of Events at Mount St. Helens
- May 18, 1980 - Mount St. Helens erupts
- May 23, 1980 - Columbia River shipping channel partially cleared
- June, 1980 - Congress appropriates funds for St. Helens response
- November, 1980 - Shipping channel fully restored
- Winter, 1980 - Toutle River retaining structure built
- May, 1981 - Dredging from upper Toutle River basins ends
- September, 1981 - Maintenance ends at retaining structures
- August 19, 1982 - State of emergency declared at Spirit Lake
- November 5, 1982 - Pumping begins at Spirit Lake
- January, 1983 - Dredging from lower Toutle basins begins
- June 5, 1984 - Bids open for tunnel construction
- July, 1984 - Tunnel construction begins
- March 4, 1985 - Tunnel boring completed
- April 1, 1985 - Pumping ends at Spirit Lake
- May 6, 1985 - Tunnel begins operating
- August 15, 1985 - President signs Supplemental Spending Bill
- September, 1985 - Spirit Lake level reaches design elevation
- October 15, 1985 - Corps formally presents plan for SRS
- April 26, 1986 - Local cooperation agreement signed for SRS
- July 2, 1986 - Initial SRS construction funding authorized
- September, 1986 - SRS site clearing contract awarded
- December, 1986 - SRS construction begins
- November, 1987 - SRS begins sediment collection
- December, 1989 - SRS construction completed
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