The primary source of Platte Lake's water is inflow from the Upper Platte River. Outflow from the lake enters the Lower Platte River, which then passes through the Sleeping Bear Dunes National Lakeshore and finally into Lake Michigan. Average inflow to Platte Lake is approximately 120 cubic feet per second (about 3.3 million gallons per hour). At this rate, the residence time for water in the lake is about 6 months. This represents a relatively fast turnover of the lake's water; the water residence time for other area lakes is on the order of several years. This rapid turnover rate is one of Platte Lake's most unusual features; it links the lake to its watershed in a very direct way.
Historically, Platte Lake has been regarded as a high-quality body of water. Even before the surrounding area was significantly settled, and when transportation to the area was difficult at best, word of Platte Lake's charms drew sportsmen from other areas of the country. An interesting article from an old sporting magazine describes the lake at the turn of the last century.
Big Platte Lake is located in Benzie County near the Village of Honor in northwest lower Michigan. It is approximately 3.3 miles long and 1.6 miles wide, covers approximately 2550 acres, has a maximum depth of 95 feet and an average depth of 24 feet.
