Gilbert Pit Lake

Gilbert Pit Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. Gilbert Pit Lake is unusually deep for Minnesota at 443 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. The lake's 243 acres and 5.8 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 187 graded lakes in St. Louis County, Gilbert Pit Lake sits at rank 76, above the county median.

Zebra mussels have been documented at Gilbert Pit Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. The fishery includes walleye alongside the lake's other 10 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.