Big Carnelian Lake

Big Carnelian Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season.

Trophically, Big Carnelian Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. Big Carnelian Lake is unusually deep for Minnesota at 66 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. The lake's 457 acres and 5.1 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Among the 31 graded lakes in Washington County, Big Carnelian Lake ranks 7 — in the top quartile locally.

Big Carnelian Lake is on the Minnesota infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. The fishery includes walleye among the lake's 12 documented species — a notable draw for Minnesota anglers. A documented public access point at Big Carnelian Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been recorded 23 times at Big Carnelian Lake, with a median around Apr 9. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.