Ever wonder why Lake Saint Clair is sometimes called the sixth Great Lake? It’s a freshwater lake nestled between Ontario, Canada, and Michigan. Lake Saint Clair isn’t officially one of the Great Lakes. But it is still a vital part of the Great Lakes system.
Back in 1679, French Catholic explorers named it Lac Sainte-Claire. They named it after Saint Clare of Assisi. They first saw the lake on her feast day.
Lake Saint Clair connects Lake Huron to the north with Lake Erie to the south. It does so via the St. Clair River and the Detroit River.
This lake isn’t very deep. Its average depth is only about 11 feet. But don’t worry, there’s a deeper channel. Government agencies keep a 30-foot-deep shipping channel open. This ensures ships can pass safely.
Fun fact. The Canadian territory around Lake Saint Clair sits south of the United States territory. That’s a bit unusual.
Lake Saint Clair measures about 26 miles from north to south. It is also about 24 miles from east to west. That’s a surface area of about 430 square miles.
The St. Clair River flows into Lake Saint Clair from Lake Huron. It creates a large river delta. This delta is the largest in the Great Lakes system. Other rivers feeding Lake Saint Clair include the Thames, the Sydenham, and the Clinton River. Water flows out of Lake Saint Clair into the Detroit River. Then it flows into Lake Erie.
The water doesn’t stay long in Lake Saint Clair. The average time is only about seven days. This can change depending on wind and water flow.
Native Americans knew this lake well. The Mississauga called it Waawiyaataanong. It means at the whirlpool. Early French mapmakers had many names for it. One was Lac des Eaux de Mer. That means Seawater Lake. Others referred to sweetness. Because the lake was freshwater, not saltwater.
French explorer Sieur de La Salle arrived here in 1679. He named it Lac Sainte-Claire.
By 1755, English maps showed the name as St. Clair. Some think it honors General Arthur St. Clair. But the name existed before he was famous.
The lake’s location affects its water clarity. Despite past pollution, the water quality is now quite good. Many cities get their drinking water from this lake.
In the 1970s, there were concerns about mercury. The Dow Chemical Chlor-Alkali Plant in Sarnia, Ontario, contaminated the fishery. The fishery has not reopened. But mercury levels are now safe. Sport fishing remains popular.
Many boat and yacht clubs dot the shores of Lake Saint Clair.
There are many public beaches here, too.
So next time you hear someone call Lake Saint Clair the sixth Great Lake, you’ll know why. It’s a vital and fascinating part of the Great Lakes system. It has a rich history and continues to be important today.