Adjoining the city of
Ottertail, it is a part of the
Otter Tail River chain of lakes. Upstream from the lake are Big Pine, Little Pine and Rush lakes, while downstream are East Lost, West Lost and Deer lakes.
Lake Blanche (Minnesota) also flows into Otter Tail Lake. The maximum depth is , but 57% of the lake is deep or less. The shore of the lake and at least the shallower areas are composed of sand and gravel. The
water clarity is , which is considered good. A prominent feature of Otter Tail is the "point" which essentially divides the lake into eastern and western halves. Otter Tail lake is ringed with a tall, mostly
deciduous tree line. In general, the tree line goes back around 300 yards from the shore and acts as a windbreak, keeping the shoreline calm compared to the center of the lake. The waters of Otter Tail Lake ultimately flow north into
Hudson Bay through the
Red River of the North. At 13,725 acres it is the tenth largest lake completely within the borders of Minnesota. == Recreation ==