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LakeQuality
F

Unn Pond

Dakota County, MinnesotaHypereutrophic

Unn Pond earns an F: 135 µg/L of phosphorus and clarity at 2.0 ft signal heavy nutrient loading from the surrounding watershed. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Hypereutrophic conditions mean the lake is operating at the upper end of the productivity scale, with all the bloom risk that implies. 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. Unn Pond ranks 31 of 36 in Dakota County — at the lower end of the locally monitored distribution.

Unn Pond has no invasive species recorded in Minnesota state databases as of 2024, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Unn Pond, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-25. Grade methodology: LakeGrade methodology.

Swimming Safety

Avoid swimming, very poor water quality, potential algae toxins

Water Quality Grade: F, Very Poor

Very murky, less than 2 ft of visibility. Phosphorus level: 135 µg/L. Trophic State Index: 71.

MetricValueGrade
Water Clarity (Secchi Depth)2 ftF
Phosphorus135 µg/LF
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)71Hypereutrophic

Very high nutrients, dense algae, poor clarity

Water Quality Trend: Declining

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

MetricTrendChange/YearYears
Water Clarity Declining-0.041 m/yr5
Phosphorus Declining+1.5 µg/L/yr5
Chlorophyll-a Declining+7 µg/L/yr2
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (6 observations).

Typical Ice-Out
Apr 6
EarliestLatest
Ice-Out2003-03-30 (2003)2008-04-17 (2008)
Ice-In2007-11-28 (2007)2004-12-11 (2004)

Most recent ice-out: 2008-04-17

Location

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County Ranking

Ranked #31 of 36 lakes in Dakota County

Cleaner Lakes Within 30 Miles

Unn Pond holds Grade F. 5 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Dakota County

Hypereutrophic Lakes in Minnesota

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Ice data from Minnesota DNR Climate

Most recent sample: 2024-09-25

Monitoring stations: 1