Elmo Lake

On the LakeGrade scale Elmo Lake grades a B, with clarity at 11.2 ft and phosphorus readings still being added placing it above the Minnesota median. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Mesotrophic conditions dominate at Elmo Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. At 140 ft of maximum depth, Elmo Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. The lake's 257 acres and 4.1 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, Elmo Lake sits at rank 8, above the county median.

Eurasian watermilfoil is established at Elmo Lake, which can dampen recreational access and pressure the native plant community. Walleye are documented at Elmo Lake, one of 13 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.