- The Mississippi River Valley and Lake Pepin were formed when the large glacial Lake Agassiz began flowing southward, near the intersection of Minnesota and North and South Dakota, through the glacial Warren River about 12,000 years ago. The massive flow of water decreased several thousand years later as the glacier receded and the waters began flowing in other directions. About 9,500 years ago sand, which was deposited at the Chippewa River delta where it joined the Mississippi River, acted as a damn and Lake Pepin was formed.
- At one time the Lake extended to St. Paul, but as the flow of water decreased and more sediment was deposited it gradually assumed its present day size of 1 to 2 ˝ miles wide and 22 miles long. The surface of the lake is 644 feet above sea level and the tops of the surrounding bluffs are about 450 feet above the level of the lake. The average water retention time in the lake is 19 days.
- In the late 1600s the lands around the lake were under the control of the Dakota Sioux, but their ownership was disputed by the Chippewa at the lower end of the lake. The dispute led to many battles between the two tribes. In 1837 the Sioux relinquished their claim, but the battles over ownership lasted until 1851. The Indian name for the river was "Mech-e-sebe" which meant "great river." Their name for the lake was "Menah - Tongo." The first white explorer to see the lake was Father Louis Hennepen, who canoed through the lake in 1680. One story relates that he named the lake "Lac Des Pleus" (Lake of Tears), when he was a prisoner of Sioux tribesmen and several of them cried as they danced as they were determining if he should be put to death. Later another explorer (Charlevoix) called the lake "Lac de bon Secours" (Good Help).
- Father Hennepen reached the source of the Mississippi River in 1682 and at that time claimed all of the Mississippi Valley in the name of France. The area included all of the land that became known as the Louisiana Territory, which was purchased by the United States from France in 1803 for fifteen million dollars. The name "Lake Pepin" was given to the lake by two French explorers in honor of "Pepin the Short" who ruled France from 740 to 768 AD and was the father of Charlemagne. In the early sixteen hundreds King Louis X111 of France gave two French brothers, Guillaume dit Trancheviontage and Eugene Pepin De la Fond, a large land grant in Canada. Two of Guillaume's sons, Pierre and Jean Pepin, were exploring in this area in 1679 and gave the lake its present name. The lake first appeared on a map that was published in 1682, but was unnamed. Several French forts were constructed along the lake in the late sixteen and early seventeen hundreds, although most of their locations are still controversial.
- Maps published at that time show two forts located on the banks of Lake Pepin. Nicolas Perrot explored the upper Mississippi River from 1665 until 1695 and built the first fort, Fort St. Antione, between the present villages of Pepin and Stockholm in 1686. He was at the fort in 1869 when he proclaimed possession of all the lands along the upper Mississippi River in the name of France. A preliminary archaeological dig at the site in 1994 revealed old French artifacts, but some historians feel that they were from a fort built in the mid seventeen hundreds and that the actual site of Fort St. Antione was located at Pepin prairie, which is east of the village of Pepin. Fort Bon Secours was built on the Minnesota side of the river below the lake and above Wabasha in the late 1680's. It was also called Fort Le Sueur and latter Fort Perrot on several different maps.
- In 1695 Le Sueur built a fort on "Isle Pele" near Treasure Island and the mouth of the St. Croix River. The most confusing accounts of a French fort location is that of Fort Beauharnias (pronounced "born - wah"), which was also known as "The Sioux Post," and was built in 1727 by Rene Boucher on a site along the banks of the lake. Its location was thought to be on Sandy Point (Pt du Sable) below Frontenac, but exploratory digs 25 years ago failed to find any French artifacts in that area. It was abandoned after a year, but was rebuilt and occupied in 1730 to 1737 and again in 1750 to 1759. These dates differ in several journals that have published. At this time the actual site of the fort has not been determined. In 1763 the British took control of the land around Lake Pepin. The first English explorer in this area was Jonathan Carver, who arrived in 1766. He was the first white to canoe down the Chippewa River and later published notes and maps about this area in England.
- He produced a document stating that a large tract of land was given to him by the Sioux. It included all of the land East of the Mississippi River for 200 miles below St. Anthony Falls, then 120 miles East to the source of the Pine River, and then 150 miles North and then a straight line back to the falls. The document is still available for research, but his claim was never honored. During the late seventeenth, eighteenth and early nineteenth Centuries most of the European activities around Lake Pepin were exploration, the establishment of forts and fur trading with the Native Americans. There were vast tracts of White Pine forests in Northern Minnesota and Wisconsin and in the late eighteen thirties their harvest began.
- The logs were floated down the St. Croix and Chippawa Rivers, formed into rafts, some containing as much as ten million board feet of lumber, and pushed by steamboats down the Mississippi River. By the early nineteen hundreds much of the timber had been harvested and the last raft to leave our area was in 1915. Another major industry along the lake began in the late eighteen hundreds when the harvesting of fresh water mussels and clams for buttons and pearls began. Approximately one in a hundred clams contain pearls, while one in ten thousand contain perfectly round pearls.
- The use of the mussel and clam shells for buttons ended in the nineteen forties, but some individuals still dive in the lake looking for pearls. The infestation of the lake by Zebra Mussels may have ended their search. After the "River and Harbor Act" was passed in 1930 and the construction of the dams along the upper Mississippi River were finished; the transportation of farm produce, petroleum, chemicals, and manufactured goods in barges pushed by tugs began. Last year nearly twelve hundred tugs pushing barges carrying over twelve million pounds of materials passed through Lake Pepin. Their passage through the lake usually begin in mid March and stop near the end of November.
- The surface of the lake usually freezes in early December with the ice becoming more than twenty-four inches thick in some places. This allows cars to travel on the lake, but one should be familiar with the lake before driving on its surface. During the winter season the lake is used for ice fishing, skating, sailing and cross-country skiing. The lake usually opens in March, then the barge traffic, fishing and sail-boating begins anew.