# Lake Pepin *Lake on the Mississippi River between Minnesota and Wisconsin; site of the 1830 Lake Pepin Tract and subject of a 2025 federal suit* Lake Pepin is a naturally formed widening of the [[Mississippi River]] where the river marks the boundary between [[Minnesota]] and Wisconsin. It sits in a valley cut at the close of the last Ice Age by the outflow of a vast glacial lake, and it ranks fourth in size among Wisconsin's lakes.[^1] Water, highway and rail routes now run along its shores.[^1] West of the lake lay the Lake Pepin Tract. The 1830 [[Treaty of Prairie du Chien]] established it, and it covered about 320,000 acres, roughly twenty-five by thirty-two miles.[^2][^3] On October 13, 2025, which was [[Indigenous Peoples' Day]], descendants who identify as [[Mdewakanton]] or "half-breed" Sioux sued the United States in the U.S. Court of Federal Claims over that reservation. They seek about $5 billion and federal recognition.[^4][^5] The suit rests on the 1830 treaty and on the 1851 Treaties of Traverse des Sioux and Mendota, which the plaintiffs allege removed the reservation's protections. The matter was pending as of the record.[^4][^5] ## Geography The lake has a surface area of about 40 square miles and an average depth of 21 feet. It is as much as 2 miles across and about 22 miles from end to end.[^1] Its broad stretch runs from Bay City, Wisconsin, at the north to Reads Landing, Minnesota, at the south. Pepin, Maiden Rock and Stockholm lie on the Wisconsin shore, and Frontenac State Park covers much of the Minnesota shore. Lake City, Minnesota, is the biggest waterfront city.[^1] Rail lines follow both banks. U.S. Route 61 runs on the Minnesota side and Wisconsin State Highway 35 runs on the Wisconsin side, and both roads are designated National Scenic Byways.[^1] ## Geology The valley the lake occupies was carved by Glacial River Warren, which drained Lake Agassiz. The modern lake formed when the Chippewa River deposited a delta of sediment near [[Wabasha]], at the south end, and the river backed up behind it.[^1] In the roughly 10,000 years since, continued sedimentation has moved the lake's upper end about 80 km (50 mi) downstream to its present position near Red Wing, Minnesota.[^1] ## Ecology Sediment carried down the river still settles where the current slows at the lake's head, and the rate has increased. The Lake Pepin Legacy Alliance calls the result a "wet desert" because of the threat it poses to the lake's native plants.[^1] Some attribute the rise mainly to farm run-off along the [[Minnesota River]]. Other research points to a broader set of processes, including natural bank sloughing, limits on river flooding and the straightening of channels, and some studies tie the acceleration to heavier precipitation under climate change.[^1] ## Human history Guillaume Delisle's 1703 map of New France is the first to name the lake. The name honors Jean Pepin, who settled on its shores in the late 1600s.[^1] Nicolas Perrot built Fort Saint Antoine, the earliest of several fur-trade posts on the lake, in 1686. In 1727 René Boucher de La Perrière and Father Michel Guignas built Fort Beauharnois, which was moved to higher ground in 1730.[^1] A deed known as [[Carver's Grant]] is dated "the Great Cave, May the 1st, 1767" and bears the names of two Sioux chiefs. It claimed about 10,000 square miles on the east bank of the Mississippi from the [[Falls of St. Anthony]] to Lake Pepin. According to the Wisconsin Historical Society, heirs petitioned Congress around 1804. In 1817, congressional investigators learned from Sioux elders in St. Paul that "no chiefs with the names on the deed had ever existed." Congress rejected the claim on January 29, 1823.[^6] The 1830 Treaty of Prairie du Chien set aside the Lake Pepin Tract west of the lake.[^2][^3] The current federal suit alleges that the 1851 cessions at Traverse des Sioux and Mendota removed the tract's protections.[^4][^5] From the 1840s, loggers floated cut timber across the lake, often with steamboats helping against wind and slack current. Rafts were assembled at Reads Landing and towed downstream to mills at Winona and St. Louis.[^1] In 1890 the ferry *Sea Wing* overturned in a storm on the lake and 98 people died.[^1] Water skiing is credited to Ralph Samuelson of Lake City, who first did it on the lake in 1922.[^1] ## Popular culture Laura Ingalls Wilder was born in Pepin, Wisconsin. The lake appears in *Little House in the Big Woods*, and her family crosses it on the ice in the first chapter of *Little House on the Prairie*.[^1] ## In the Minnesota record ### Who The plaintiffs are descendants who identify as Mdewakanton or "half-breed" Sioux of the Lake Pepin Reservation. They are represented by counsel [[Erick Kaardal]].[^4][^5] ### What *[[Mdewakanton / Sioux half-breed descendants v. United States (Lake Pepin reservation; federal recognition)]]* concerns the reservation set aside by the 1830 Treaty of Prairie du Chien.[^4][^2] As the plaintiffs plead it, the suit is also grounded in the 1851 Treaties of Traverse des Sioux and Mendota.[^4] ### When - 1830: the Treaty of Prairie du Chien establishes the Lake Pepin Tract.[^2] - 1851: the plaintiffs allege that the Traverse des Sioux and Mendota cessions removed the tract's protections.[^4] - October 13, 2025: the suit is filed; its status as of the record is pending.[^4][^5] ### Where The suit was filed in the U.S. Court of Federal Claims.[^4] The tract it concerns lay west of Lake Pepin.[^2] ### Why The complaint seeks federal recognition for the descendants together with monetary relief.[^4][^5] ### How The plaintiffs allege that the reservation clause was removed in the 1851 cessions without the consent of the Mdewakanton descendants.[^4][^5] The record does not include a court finding on that allegation.[^4] ### How much - Relief sought: about $5 billion.[^4][^5] - Tract: about 320,000 acres.[^2][^3] ## See also - [[Lake Pepin Half-Breed Tract]] - [[Treaty of Prairie du Chien]] - [[Carver's Grant]] - [[Minnesota Historical Society]] ## Notes [^1]: Wikipedia contributors, *Lake Pepin* (rev. 1367751141, retrieved Oct. 26, 2026; CC BY-SA 4.0) — geography, geology, ecology, history and culture of the lake. https://en.wikipedia.org/wiki/Lake_Pepin [^2]: Minnesota Historical Society, MNopedia, *Lake Pepin Tract* — established by the 1830 Treaty of Prairie du Chien; 320,000 acres west of Lake Pepin, roughly twenty-five by thirty-two miles. https://www.mnhs.org/mnopedia/search/index/place/lake-pepin-tract [^3]: Wikipedia contributors, *Lake Pepin Half-Breed Tract* — the tract set aside west of the lake. https://en.wikipedia.org/wiki/Lake_Pepin_Half-Breed_Tract [^4]: Plaintiffs, *Complaint*, U.S. Court of Federal Claims (filed Oct. 13, 2025; mirrored on turtletalk.blog) — the Mdewakanton / Lake Pepin descendants' claims for federal recognition and relief under the 1830 and 1851 treaties; pending as of the record. https://turtletalk.blog/wp-content/uploads/2025/10/complaint.pdf [^5]: CBS News Minnesota, report on the Sioux descendants' lawsuit against the United States (Oct. 2025) — the filing, counsel Erick Kaardal, and the approximately $5 billion and federal recognition sought. https://www.cbsnews.com/minnesota/news/sioux-descendants-announce-lawsuit-united-states-land-recognition/ [^6]: Wisconsin Historical Society, *Carver's Grant* (record CS1987) — 1767 deed; extent from the Falls of St. Anthony to Lake Pepin; 1817 finding from Sioux elders; Congress's rejection on Jan. 29, 1823. https://www.wisconsinhistory.org/Records/Article/CS1987