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Mountain County Park and Historic Site

Cottonwood County Historical Society
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View of old "mountain" island, Mountain Lake

Mountain County Park in Cottonwood County, July 2, 2014. Photograph by Wikimedia Comons user McGhiever. CC BY-SA 3.0.

Cottonwood County’s now-dry Mountain Lake was the site of Indigenous villages and encampments over the course of 3,000 years. The area has provided clues—some of the oldest evidence of human habitation in present-day Minnesota—about the lives of a group of people who remained relatively isolated from Upper Mississippi trade networks. In the 1970s, the site was developed into a public park operated by Cottonwood County.

Named by William Mason for the raised island in its center, Mountain Lake shows a near-continuous record of human activity stretching back 3,000 years. In 1976, an archeological team led by Joseph Hudak carrying out a dig there found traces of an ancient village. Carbon dating determined the remains of a round dwelling on the site to be roughly 2,100 years old, making it the oldest dwelling yet found in Minnesota. The amount of material uncovered on the dwelling site indicated that it had been used for only one winter season, making it a remarkably intact snapshot of life in the Middle Woodland period.

Because shards of decorated pottery from the village site are similar to those found on nearby islands, archaeologists have identified the Mountain Lake village as part of the “Fox Lake focus,” named for a village site on nearby Fox Lake. The Fox Lake people lived on islands in present-day Southwestern Minnesota from approximately 100 BCE to 850 CE, hunted buffalo, and had a unique style of pottery featuring wide mouths and impressions made with cord-wrapped paddles.

The Fox Lake people seem to have used items like certain types of hide scrapers and crushed-shell pottery later than groups to the east, indicating that they remained isolated from the river trade routes used by the Upper Mississippian (Oneota) culture. Anthropologist Karl Schlesier has found evidence that the Fox Lake group—possible ancestors of Crow and Hidatsa people—later migrated northwest into present-day central North Dakota. Artifacts like crushed shell pottery and certain types of hide scrapers indicate that the Mountain Lake area was eventually inhabited by Oneota groups, whose descendants include the Ho-Chunk, Otoe, Iowa, and Missouria.

In the 1870s and 1880s, Mountain Island was a source of wood fuel for the settler-colonists who moved to Cottonwood County. In the early 1890s, it seemed an ideal place for a summer resort. However, the lowland area surrounding the lake was swampy, and the island was difficult to reach. Mountain Lake was drained between 1905 and 1906 for additional farmland, and farmers raised produce on the fertile lakebed for the next several decades. A road was built to provide access to the island.

Interest in the mountain grew in the 1950s when flint arrowheads were found by Sam Franz, whose father owned the farmland surrounding the old island. Excavations at the site led by Lloyd Wilford in 1956 uncovered a “deeply stratified village site” and indicators that it had been occupied from the Late Archaic through the Middle Woodland periods. Further excavations by Wilford seven years later identified similarities in the form of arrowheads and pottery with nearby sites.

As a result of these surveys, Mountain Park was placed on the National Register of Historic Places on June 4, 1973. To prevent damage to the culturally significant site, construction of campground facilities was kept to the side of the island, which had previously been submerged. Some of the dig’s findings were displayed at the Science Museum of Minnesota in St. Paul; a replica of the round dwelling and some of the artifacts found at the site were also displayed at Heritage House in Mountain Lake.

Cottonwood County bought Mountain Park from Franz in November of 1976, and major development proceeded in 1979 with the assistance of the Law and Conservation Fund (LAWCON). Roads, toilets, trails, a picnic shelter, entry signage, and a well were built at a cost of $31,000.

The undeveloped rise of the former island at Mountain Park is a superior site for observing wildlife and birds of many species. In 2019, visitors can view a wide array of wildlife in this relatively undisturbed area and enjoy campgrounds and picnic sites nearby.

Editor’s note: Dates provided prior to 1800 are approximate and based on a combination of carbon-14 dating and comparison of cultural elements similar to those found at other area sites. There is debate among archaeologists over whether “Middle Woodland” is the appropriate terminology for dating in this region; the term is included here for the sake of wider familiarity.

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© Minnesota Historical Society
  • Bibliography
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Anfinson, Scott, ed. Southwestern Minnesota Archaeology: 12,000 Years in the Prairie Lake Region. Minnesota Prehistoric Archaeology Series 14. St. Paul: Minnesota Historical Society, 1997.

The Centennial History of Cottonwood County, Minnesota. [Windom?: MN]: N.p., 1970.

Centennial Committee on the Occasion of our Communities’ 106th Anniversary. Mountain Lake 1886-1986. Consultation and Composition by Gary Richter.

Florin, Frank, and James Lindbeck. “Phase I Archaeological Survey And Phase II Evaluation Of Site 21PL109 for the County State Aid Highway 1 Reconstruction And Bridge Replacement Project In Polk County, MN.” Boyceville, WI: Florin Cultural Services, December 2017.

Hudson, Lew. “State’s Oldest Human Dwelling Believed Found Near Mt. Lake.” Worthington Globe, July 10, 1976. Reprinted in Minnesota Archaeologist 39, no. 1 (February 1979): 26‒32.

Johnson, Elden. “Nomination Form: Mountain Lake Site." National Register of Historic Places inventory, December 27, 1971. N73000973. State Historic Preservation Office, St. Paul.

National Park Service. The National Register of Historic Places Supplement, 1974. Washington, DC: US Department of the Interior, 1974.

“Park Season Winds Down.” Cottonwood County Citizen, October 10, 2001.

Schlesier, Karl H. “Commentary: a History of Ethnic Groups in the Great Plains, A.D. 150‒1550.” In Plains Indians, A.D. 500–1500: The Archaeological Past of Historic Groups, 335‒46. Norman, OK: University of Oklahoma Press, 1994.

Upham, Warren. “Mountain Lake Township.” Minnesota Place Names. 3rd edition. St. Paul: Minnesota Historical Society, 2001.

Related Images

View of old "mountain" island, Mountain Lake
View of old "mountain" island, Mountain Lake
Map of Mississippian cultures
Map of Mississippian cultures
Sherds of Fox Lake-type ceramics
Sherds of Fox Lake-type ceramics

Turning Point

Cottonwood County buys Mountain Lake County Park from Sam Franz in November of 1976.


500 BCE

Indigenous people live in the vicinity of Mountain Lake.

100 BCE

The Fox Lake people develop a unique style of pottery, indicating that their village sites at Fox Lake, Mountain Lake, and Lake Benton may have been becoming more permanent at this time.

850 CE

The Fox Lake group migrates northwest to a region spanning present-day Central North Dakota. Similar pottery shards found at the Devils Lake‒Sourisford burial complex suggest that they are ancestors of the Crow and Hidatsa.

900 CE

The Southwestern prairies of Minnesota are inhabited by people identified by archaeologists as the “Great Oasis” group. While they also hunted buffalo seasonally, these predecessors of the Mandan lived in more permanent villages than the Fox Lake group.

800‒1750 CE

Shell-tempered vessels, seeds, and hide scrapers found at Mountain Lake that date to this period indicate the influence of the Oneota culture in the area.


Mountain Lake is drained for additional farmland; farmers grow vegetables and sunflowers.


Local farmer Stephen Franz finds flint and chert arrowheads in the vicinity of the lake.


Archaeologist Lloyd A. Wilford excavates the Mountain Lake site (21CO0001). The artifacts he finds at multiple dig sites, combined with high phosphate levels, indicate that Mountain Lake was the site of human activity for thousands of years.


The eighty-acre Mountain Lake Site (21PL109) is added to the National Register of Historic Places on June 4.


An archaeological survey organized by the Minnesota Science Museum and led by Joseph Hudak uncovers artifacts and cultural data from inhabitants dating back to 500 BCE.


Cottonwood County buys land adjacent to Mountain Lake from the Franz family.


Cottonwood County receives financial support from the Law and Conservation Fund (LAWCON) to develop Mountain County Park. Park pavilions and shelters are used for picnics and family reunions.


The relatively undisturbed original “mountain” portion of the Mountain Lake Park is a popular destination for birdwatching, and is used by the Cottonwood County Bird Club for their annual counts.