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LakeQuality
A

Emerald Lake

Beltrami County, MinnesotaOligotrophic

Emerald Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Beltrami County. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Trophically, Emerald Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Among the 86 graded lakes in Beltrami County, Emerald Lake ranks 5 — in the top quartile locally.

Emerald Lake has no invasive species recorded in Minnesota state databases as of 2025, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Emerald Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. 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.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-23. Grade methodology: LakeGrade methodology.

Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

Crystal clear, you can see 31.2 ft down. Phosphorus level: 12 µg/L. Trophic State Index: 34.

MetricValueGrade
Water Clarity (Secchi Depth)31.2 ftA
Phosphorus12 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)34Oligotrophic

Low nutrients, clear water, excellent for swimming

Water Quality Trend: Improving

Based on 6 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.657 m/yr6
Phosphorus Improving-0.99 µg/L/yr6

Location

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County Ranking

Ranked #5 of 86 lakes in Beltrami County

Nearby Lakes in Beltrami County

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2025-09-23

Monitoring stations: 1