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Federal
Three Sisters, Mt. Jefferson, and Mt. Washington wilderness areas in Oregon: 1991 visitor survey data
Department of Agriculture —
This data publication contains 1991 permit information and mail-back survey responses from visitors to the Three Sisters, Mt. Washington, and Mt. Jefferson Wilderness... -
Federal
Results of repeated leveling surveys near the Three Sisters volcanic center, central Oregon, 2002-2008
Department of the Interior —
This Data Release includes results of repeated leveling surveys each summer from 2002 to 2006 and in 2008 along two short traverses in the Three Sisters Wilderness...