Okanagan Lake, British Columbia, Canada August, 1997 The southern portion of Okanagan Lake can be seen in this west-looking view. Located in a prosperous fruit-growing region of Southern British Columbia, Okanagan Lake is 69 miles (111 km) long and from 2 to 4 miles (3 to 6 km) wide. The lake is fed by and its outlet is the Okanagan River, which flows southward and joins the Columbia River in the state of Washington. The lake is a popular all-season resort region for fishing and camping in the summer and skiing and cross-country skiing during the winter