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C

Miller Lake

Carlton County, MinnesotaEutrophic

Miller Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. Secchi readings are the weakest of the scored parameters, suggesting suspended sediment or algal biomass dominates the optical signal.

At a TSI of 53, Miller Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. 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. Miller Lake sits at rank 20 of 33 in Carlton County, in the lower half of the local distribution.

No invasive species are currently listed at Miller Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Miller Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. Public access is available — the lake is on the Minnesota PCA public-access list. The grade is supported by multiple sampling years from Minnesota PCA volunteers and partner agencies, giving the letter a reasonably stable foundation.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-17. Grade methodology: LakeGrade methodology.

Reviewed by LakeQuality Editorial Team · Updated

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Swimming Safety

Generally safe for swimming, moderate water quality

Water Quality Grade: C, Fair

Very murky, less than 1.8 ft of visibility. Phosphorus level: 32 µg/L. Chlorophyll-a: 1.6 µg/L. Trophic State Index: 53.

MetricValueGrade
Water Clarity (Secchi Depth)1.8 ftF
Phosphorus32 µg/LC
Chlorophyll-a (Algae)1.6 µg/LA
Trophic State Index (TSI)53Eutrophic

High nutrients, frequent algae, reduced clarity

Water Quality Trend: Improving

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+2.237 m/yr5
Phosphorus Improving-13.5 µg/L/yr2
Chlorophyll-a Improving-0.9 µg/L/yr5
See year-by-year chart →

Location

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County Ranking

Ranked #20 of 33 lakes in Carlton County

Cleaner Lakes Within 30 Miles

Miller Lake holds Grade C. 5 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Carlton County

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Miller Lake. 2 reports on file.

EPA Impairment Status

Miller Lake is officially listed as impaired under Clean Water Act §303(d) in the 2019 EPA reporting cycle.

Causes of impairment

Mercury

Source: EPA ATTAINS assessment unit FDL_112 · Official waterbody report · Matched by proximity (0.01 km)

Data Sources

Water quality data from the EPA Water Quality Portal

Impairment status from EPA ATTAINS 303(d) database

Grading methodology based on Metropolitan Council standards

Most recent sample: 2024-10-17

Monitoring stations: 1