View source for Three Sisters Wilderness

{{Short description|Wilderness area in Oregon, United States}}
{{Use American English|date=July 2025}}
{{Use mdy dates|date=January 2025}}
{{Infobox protected area 
| name = Three Sisters Wilderness
| iucn_category = Ib
| photo = Middle and South Sister, looking north.jpg
| photo_width = 300px
| photo_caption = Aerial view of the wilderness, showing Middle Sister (left) and South Sister
| location = [[Lane County, Oregon|Lane]] / [[Deschutes County, Oregon|Deschutes]] counties, [[Oregon]], [[United States|USA]]
| nearest_city = [[Sisters, Oregon|Sisters, OR]] (20 miles NE)<br />[[Bend, Oregon|Bend, OR]] (20 miles E)
| coordinates = {{coord|44|05|N|121|57|W|display=inline, title}}
| area_acre = 286,708
| established = September 3, 1964 (date of official designation under the [[Wilderness Act]])<ref>{{cite web|url=http://files.eric.ed.gov/fulltext/ED032179.pdf|title=Wilderness Users in the Pacific Northwest - Their Characteristics, Values, and Management Preferences|page=6|work=U.S.D.A. Forest Service Research Paper PNW-61|first1=John C.|last1=Hendee|first2=William R.|last2=Canon Jr.|first3=Larry D.|last3=Marlow|first4=C. Frank|last4=Brockman|year=1968|publisher=U.S. Forest Service|access-date=January 4, 2016}}</ref>
| visitation_num = 
| visitation_year = 
| governing_body = [[United States Forest Service|U.S. Forest Service]] 
}}
The '''Three Sisters Wilderness''' is a [[wilderness area]] in the [[Cascade Range]], within the [[Willamette National Forest|Willamette]] and [[Deschutes National Forest]]s in [[Oregon]], United States. It comprises {{convert|286708|acre|km2}}, making it the second-largest wilderness area in Oregon, after the [[Eagle Cap Wilderness]]. It was established by the [[United States Congress]] in 1964 and is named for the [[Three Sisters (Oregon)|Three Sisters]] volcanoes. The wilderness boundary encloses the Three Sisters as well as [[Broken Top]], which is southeast of South Sister.<ref name="wildnet">[http://www.wilderness.net/index.cfm?fuse=NWPS&sec=wildView&wname=Three%20Sisters&error=404 Three Sisters Wilderness] - Wilderness.net</ref>

Three Sisters was designated as a [[UNESCO]] Biosphere Reserve under the [[Man and the Biosphere Programme]] in 1976, and was one of 17 reserves in the United States withdrawn from the programme in June 2017.<ref name="Three Sisters">{{cite web|url=http://www.unesco.org/mabdb/br/brdir/directory/biores.asp?code=USA+24&mode=all|title=Three Sisters|access-date=2 September 2018}}</ref><ref name=UNESCO>{{cite web|url=http://www.unesco.org/new/en/natural-sciences/environment/ecological-sciences/biosphere-reserves/europe-north-america/|title=Biosphere Reserves: Europe & North America|author=UNESCO|access-date=2 September 2018}}</ref><ref name="UNESCO Press Release">{{cite web|url=https://en.unesco.org/news/23-new-sites-added-unesco-s-world-network-biosphere-reserves|title=23 new sites added to UNESCO's World Network of Biosphere Reserves|date=14 June 2017|access-date=2 September 2018}}</ref>

[[Oregon Route 242]] separates the Three Sisters Wilderness from the [[Mount Washington Wilderness]] to the north, while the [[Waldo Lake Wilderness]] shares the southern boundary.<ref name="wildnet"/>

The three peaks were known by pioneers as Faith, Hope and Charity.<ref>{{cite ogn|4th|p=544}}</ref> Nearby landmarks include The Husband, The Wife, and the Little Brother.<ref name=Friedman>{{cite book |url= https://books.google.com/books?id=4i1grNoMcWgC&pg=PA694 |title= In Search of Western Oregon |author= Friedman, Ralph |author-link= Ralph Friedman |year= 1990 |page=694 |publisher= [[Caxton Press (United States)|The Caxton Printers, Ltd]] |location= Caldwell, Idaho |isbn= 0-87004-332-3}}</ref>

==Geology==
Many types of landforms make up the wilderness area, but the most common are [[volcanic]] features, the most notable being the Cascades which are [[stratovolcano]]es having formed around 1.6&nbsp;million years ago.<ref name="USGS">{{cite web|url=https://geomaps.wr.usgs.gov/parks/province/cascade2.htm|title=Geologic Provinces of the United States: Pacific|publisher=[[United States Geological Survey|USGS]]|access-date=July 6, 2013}}{{dead link|date=December 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Numerous [[cinder cone]]s have formed on their flanks as well as many [[lava flow]]s that contain hundreds of [[lava tube]]s.<ref name="OHDG">{{cite web|url=http://ohdgrotto.caves.org/caves/caves-of-central-oregon|title=The Caves of Central Oregon|author=Matt Skeels|publisher=[[Oregon High Desert Grotto]]|access-date=July 6, 2013}}</ref>
[[File:Proxy Falls, Oregon.jpg|thumb|upright|[[Proxy Falls]] in the wilderness]]

==Topography==
The Three Sisters Wilderness ranges in elevation from {{convert|2000|to|10363|ft|m}}. The Three Sisters—North Sister at {{convert|10090|ft|m|0}}, Middle Sister at {{convert|10052|ft|m}}, and South Sister at {{convert|10363|ft|m}} — are found in the eastern portion of the Wilderness. Including [[Broken Top]]—just to the south at {{convert|9175|ft|m}} — there are 14 glaciers offering one of the best examples of the effects of [[glaciation]] in the Pacific Northwest. [[Collier Glacier]], between North and Middle Sister, is the largest [[glacier]] in Oregon.<ref name="wildnet"/>  The headwaters of the [[National Wild and Scenic River|Wild and Scenic]] [[Whychus Creek]] (formerly Squaw Creek<ref>{{cite web
 | url = http://www.fs.fed.us/r6/centraloregon/news/2005/08/050819names.shtml
 | archive-url = https://archive.today/20070813040722/http://www.fs.fed.us/r6/centraloregon/news/2005/08/050819names.shtml
 | url-status = dead
 | archive-date = August 13, 2007
 | title = Forest Service Proposes Central Oregon Name Changes
 | date = August 19, 2005
 | publisher = United States Forest Service
 }}</ref>) emerge in the Wilderness.<ref name="wildnet"/>

==Climate==
{{Weather box
|location = South Sister 44.1007 N, 121.7698 W, Elevation: {{cvt|9825|ft}} (1991–2020 normals)
|single line = y

|Jan high F = 26.5
|Feb high F = 25.8
|Mar high F = 27.0
|Apr high F = 30.5
|May high F = 39.2
|Jun high F = 46.7
|Jul high F = 57.8
|Aug high F = 57.8
|Sep high F = 52.7
|Oct high F = 42.1
|Nov high F = 30.3
|Dec high F = 25.5

|Jan mean F = 20.4
|Feb mean F = 18.4
|Mar mean F = 18.7
|Apr mean F = 21.1
|May mean F = 28.5
|Jun mean F = 35.3
|Jul mean F = 44.7
|Aug mean F = 44.8
|Sep mean F = 40.2
|Oct mean F = 32.0
|Nov mean F = 23.8
|Dec mean F = 19.6

|Jan low F = 14.3
|Feb low F = 11.0
|Mar low F = 10.3
|Apr low F = 11.6
|May low F = 17.9
|Jun low F = 23.9
|Jul low F = 31.7
|Aug low F = 31.8
|Sep low F = 27.7
|Oct low F = 21.8
|Nov low F = 17.2
|Dec low F = 13.7

|precipitation colour = green
|Jan precipitation inch = 20.23
|Feb precipitation inch = 14.71
|Mar precipitation inch = 16.25
|Apr precipitation inch = 13.2
|May precipitation inch = 9.05
|Jun precipitation inch = 5.67
|Jul precipitation inch = 1.45
|Aug precipitation inch = 1.63
|Sep precipitation inch = 4.37
|Oct precipitation inch = 11.19
|Nov precipitation inch = 19.24
|Dec precipitation inch = 23.2

|source=PRISM Climate Group<ref>{{cite web
|url= http://prism.oregonstate.edu/explorer/
|title= PRISM Climate Group, Oregon State University
|publisher= PRISM Climate Group, Oregon State University
|access-date= September 30, 2023
|quote= To find the table data on the PRISM website, start by clicking ''Coordinates'' (under ''Location''); copy ''Latitude'' and ''Longitude figures'' from top of table; click ''Zoom to location''; click ''Precipitation, Minimum temp, Mean temp, Maximum temp''; click ''30-year normals, 1991-2020''; click ''800m''; click ''Retrieve Time Series'' button.}}</ref>
}}

==Vegetation==
Forest cover in the Three Sisters Wilderness includes [[Douglas fir]], [[Abies amabilis|Pacific silver fir]], [[Abies lasiocarpa|subalpine fir]], [[Tsuga mertensiana|mountain hemlock]], [[Tsuga heterophylla|western hemlock]], [[Pinus contorta|lodgepole pine]] and [[Pinus ponderosa|ponderosa pine]]. A large area of the wilderness above [[tree line|timberline]] contains [[taiga|alpine]] meadows.<ref name="usfs">[http://www.fs.usda.gov/r06/willamette/recreation Three Sisters Wilderness] - Willamette National Forest</ref>

==Recreation==
[[File:Three_Sisters_Wilderness.JPG|thumb|Hikers in the wilderness south of South Sister]]

Popular recreational activities in the Three Sisters Wilderness include camping, hiking, climbing and fishing. South Sister and Middle Sister are not technically difficult climbs, but summiting North Sister requires technical expertise and equipment. More than {{convert|260|mi|km}} of trails cross the wilderness, including {{convert|40|mi|km}} of the [[Pacific Crest Trail]].<ref name="usfs"/> The {{convert|9.8|mi|km|adj=on}} [[French Pete Trail]] and its surrounding old-growth forest, a nationwide political issue in the 1970s, are located on the western edge of the wilderness near [[Cougar Reservoir]].<ref>{{cite book|last=Sullivan|first=William L.|title=100 Hikes in the Central Oregon Cascades|edition=2004|location=Eugene, Oregon|publisher=Navillus Press|pages=158&ndash;159|isbn=0-9618152-6-4}}</ref>

==See also==
[[File:Three Sisters topographic map-en.gif|thumb|Topographic map of area]]
* [[List of Oregon Wildernesses]]
* [[List of U.S. Wilderness Areas]]
* [[Wilderness Act]]

==References==
{{Reflist}}

== External links ==
{{Commons and category|Three Sisters Wilderness}}
* [http://www.fs.usda.gov/r06/willamette/recreation Three Sisters Wilderness] - Willamette National Forest
* [http://www.fs.usda.gov/r06/deschutes/recreation Three Sisters Wilderness] - Deschutes National Forest
* [http://www.wilderness.net/index.cfm?fuse=NWPS&sec=wildView&wname=Three%20Sisters Wilderness.net Wilderness information]
* [http://www.topoquest.com/map.asp?z=10&n=4888644&e=598609&s=100&size=l&u=7&datum=nad83&layer=DRG25 TopoQuest map of the Three Sisters]

{{Protected areas of Oregon}}
{{Authority control}}

[[Category:Former biosphere reserves of the United States]]
[[Category:Protected areas of Deschutes County, Oregon]]
[[Category:IUCN Category Ib]]
[[Category:Protected areas of Lane County, Oregon]]
[[Category:Wilderness areas of Oregon]]
[[Category:Willamette National Forest]]
[[Category:Deschutes National Forest]]
[[Category:1964 establishments in Oregon]]
[[Category:Protected areas established in 1964]]