Lake Alvin is an artificial lake in Lincoln County, South Dakota between Harrisburg, South Dakota and Granite, Iowa. The lake is formed by a dam on Nine Mile Creek just before it enters the Big Sioux River, east of Harrisburg. It is part of a 59 acre recreational area.

History

Lake Alvin has always been a popular swimming location for those looking for a mid-sized beach. However, in 2005, the South Dakota GFP closed the swimming beach to the public due to high levels of coliform bacteria in the lake. A shutdown was again issued in 2009, 2013, 2014, and 2020 due to high levels of coliform bacteria.