Castle Rock Lake is an artificial lake on the Wisconsin River. It is located in central Wisconsin in Adams County and Juneau County. The lake has an inflow from Petenwell Lake, Yellow River, Big Roche a Cri., and Klien Creek. It has a surface area of 16,640 acres and its depth varies from 8–20 ft in most places, with area in the old river beds reaching as de…Castle Rock Lake is an artificial lake on the Wisconsin River. It is located in central Wisconsin in Adams County and Juneau County. The lake has an inflow from Petenwell Lake, Yellow River, Big Roche a Cri., and Klien Creek. It has a surface area of 16,640 acres and its depth varies from 8–20 ft in most places, with area in the old river beds reaching as deep as 35 ft.