Lac Courte Oreilles is a large freshwater lake located in northwest Wisconsin in Sawyer County in townships 39 and 40 north, ranges 8 and 9 west. It is irregular in shape, having numerous peninsulas and bays, and is approximately six miles long in a southwest to northeast direction and with a maximum width of about two miles (3 km). Lac Courte Oreilles is in size with a maximum depth of and a shoreline of . The lake has a small inlet stream (Grindstone Creek) that enters on the northeast shore of the lake and flows from Grindstone Lake, a short distance away to the north. An outlet on the southeast shore of the lake leads through a very short passage to Little Lac Courte Oreilles, then via the Couderay River to the Chippewa River, and ultimately to the Mississippi River at Lake Pepin.