Okamanpeedan Lake, partially located in Martin County, Minnesota, and Emmet County, Iowa, is also known as Tuttle Lake. Okamanpeedan Lake is a roughly 2,300-acre (9.3 km²) riverine lake located on the East Fork of the Des Moines River. It has an average depth of about four to six feet (1.2 to 1.8 m). The lake has a contributing watershed of approximately 120,056 acres (486 km²) and watershed:lake ratio on the order of about 50:1. The lake is situated in a glacial till plain and is generally in an area dominated by loamy, poorly drained soils.