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.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | F |
| Phosphorus | 135 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 71 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.041 m/yr | 5 |
| Phosphorus | ↓ Declining | +1.5 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +7 µg/L/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (6 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2003-03-30 (2003) | 2008-04-17 (2008) |
| Ice-In | 2007-11-28 (2007) | 2004-12-11 (2004) |
Most recent ice-out: 2008-04-17
Location
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.
- AHolland LakeDakota County · 2.1 mi · Two grade letters higher (F → A)
- BCarlson LakeDakota County · 1.7 mi · Two grade letters higher (F → B)
- CJensen LakeDakota County · 1.2 mi · Two grade letters higher (F → C)
- CThomas LakeDakota County · 1 mi · Two grade letters higher (F → C)
- CPitts LakeDakota County · 1.1 mi · Two grade letters higher (F → C)
Nearby Lakes in Dakota County
More Minnesota Lake Rankings
State Parks Near Unn Pond
Other Grade F 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