Lake Francis Case is a 102,000-acre Missouri River reservoir in Gregory, Lyman, and Brule counties in south-central South Dakota — the second largest of the four Missouri River mainstem reservoirs in South Dakota and a premier walleye, smallmouth bass, and pike fishery drawing anglers from across the northern Great Plains. The lake stretches approximately 107 miles from Fort Randall Dam at the southern end to Big Bend Dam at the northern end, creating an expansive Missouri River impoundment with 540 miles of shoreline across the rolling prairie and river breaks of south-central South Dakota. The Missouri River walleye fishery on Lake Francis Case is nationally recognized — the lake produces trophy walleye in numbers that draw dedicated walleye anglers from across South Dakota, Nebraska, and Iowa specifically targeting the Francis Case corridor during the spring spawn and fall feeding periods. Smallmouth bass, northern pike, channel catfish, and white bass round out the year-round fishery. The communities of Chamberlain and Oacoma on either side of I-90 at the Missouri River crossing anchor the primary boating infrastructure and service market for the lake. Find Boat Services lists verified boat repair, motor service, electronics installation, trailer repair, and winterization providers serving Lake Francis Case within 35 miles across Gregory, Lyman, and Brule counties.