Grindstone Lake, located in Pine County 6 miles west of Sandstone, is one of the deepest lake basins in Minnesota and is an anomaly in a region dominated by 6 to 12 m deep lakes. The lake basin was scoured out by glacial erosion which removed sedimentary material that had been deposited in the pre-glacial bedrock valley. Grindstone is long and narrow, about a half mile wide, 2 miles long, and very deep. The deepest hole is 47 m deep. The lake has an average depth of 22 m, much deeper than any other lake in this region.
Grindstone is a "two-story" lake, meaning it contains habitat for both warm and cold water fish. The lake originally only had only warm water fish but has been stocked and maintained as a trout fishery. The trout are able to live in the deep, cold regions of the lake because oxic (containing oxygen) conditions persist down to ~33 m, even through the summer months.
http://www.dnr.state.mn.us/lakefind/showreport.html?downum=58012300
Grindstone Lake, located in Pine County 6 miles west of Sandstone, is one of the deepest lake basins in Minnesota and is an anomaly in a region dominated by 6 to 12 m deep lakes. The lake basin was scoured out by glacial erosion which removed sedimentary material that had been deposited in the pre-glacial bedrock valley. Grindstone is long and narrow, about a half mile wide, 2 miles long, and very deep. The deepest hole is 47 m deep. The lake has an average depth of 22 m, much deeper than any other lake in this region.
Grindstone is a "two-story" lake, meaning it contains habitat for both warm and cold water fish. The lake originally only had only warm water fish but has been stocked and maintained as a trout fishery. The trout are able to live in the deep, cold regions of the lake because oxic (containing oxygen) conditions persist down to ~33 m, even through the summer months.