Quigley Lake
Dakota County, MinnesotaHypereutrophic
On the LakeGrade rubric Quigley Lake fails the cutoffs — a TSI of 71 and persistent algal pressure put it in the bottom tier. clarity and phosphorus rate similarly, so there is no obvious single lever to pull on watershed management.
A TSI above 70 puts Quigley Lake in hypereutrophic territory: visible blooms are common, and clarity rarely climbs even in early summer. 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. Within the 36 graded lakes of Dakota County, Quigley Lake sits at rank 34, near the bottom of the county list.
No invasive species are currently listed at Quigley Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Quigley Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Quigley Lake — most use is by shoreline residents and their guests. 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 2022-09-08. Grade methodology: LakeGrade methodology.
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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: 141 µg/L. Trophic State Index: 71.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | F |
| Phosphorus | 141 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 | -0.151 m/yr | 5 |
| Phosphorus | ↓ Declining | +2.8 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +0.4 µg/L/yr | 2 |
Location
County Ranking
Ranked #34 of 36 lakes in Dakota County
Cleaner Lakes Within 30 Miles
Quigley Lake holds Grade F. 5 nearby lakes hold higher grades.
- AHolland LakeDakota County · mi · Two grade letters higher (F → A)
- BCarlson LakeDakota County · mi · Two grade letters higher (F → B)
- BBlackhawk LakeDakota County · mi · Two grade letters higher (F → B)
- CThomas LakeDakota County · mi · Two grade letters higher (F → C)
- CFish LakeDakota County · mi · Two grade letters higher (F → C)
Nearby Lakes in Dakota County
More Minnesota Lake Rankings
State Parks Near Quigley Lake
Other Grade F Lakes in Minnesota
EPA Impairment Status
Quigley Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN19-0066-00 · Official waterbody report · Matched by proximity (0.45 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: 2022-09-08
Monitoring stations: 1