Lost Lake
Hennepin County, MinnesotaHypereutrophic
Lost Lake grades an F: every scored parameter (clarity and phosphorus) rates poorly, placing it among the most stressed lakes monitored in Minnesota. clarity and phosphorus rate similarly, so there is no obvious single lever to pull on watershed management.
The hypereutrophic status — TSI 73 — reflects sustained heavy nutrient loading from the surrounding watershed and frequent algal pressure. At only 6 ft deep, Lost Lake is shallow — wind keeps the water column mixed and sediment resuspension drives phosphorus levels harder to manage. The lake is compact at 23 acres, with 0.8 miles of shoreline and little volume to buffer nutrient inputs. Lost Lake ranks 80 of 95 in Hennepin County — at the lower end of the locally monitored distribution.
Lost Lake 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 Lost Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Lost 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 2024-10-19. 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 1.5 ft of visibility. Phosphorus level: 138 µg/L. Trophic State Index: 73.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.5 ft | F |
| Phosphorus | 138 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 73 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 6 ft |
| Surface Area | 22.98 acres |
| Shoreline Length | 0.8 mi |
| Littoral Zone | 100% |
| Public Access | No |
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.022 m/yr | 5 |
| Phosphorus | ↓ Declining | +19.75 µg/L/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (8 observations).
Estimated open water season: 237 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2017-03-07 (2017) | 2008-04-18 (2008) |
| Ice-In | 2023-11-16 (2023) | 2021-12-21 (2021) |
Most recent ice-out: 2022-04-08
Location
County Ranking
Ranked #80 of 95 lakes in Hennepin County
Cleaner Lakes Within 30 Miles
Lost Lake holds Grade F. 5 nearby lakes hold higher grades.
- BPomerleau LakeHennepin County · mi · Two grade letters higher (F → B)
- CSchmidt LakeHennepin County · mi · Two grade letters higher (F → C)
- CMedicine LakeHennepin County · mi · Two grade letters higher (F → C)
- CBass LakeHennepin County · mi · Two grade letters higher (F → C)
- DMeadow LakeHennepin County · mi · Higher grade (F → D)
Nearby Lakes in Hennepin County
More Minnesota Lake Rankings
State Parks Near Lost Lake
Other Grade F Lakes in Minnesota
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 1979-08-08 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Hybrid Sunfish | 0.33 | 0.3 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
From the 1979-08-08 survey
Only one hybrid Sunfish was taken in three trap nets.
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Lost Lake. 1 report on file.
- —Fisheries Lake Survey — LostFisheries Lake Survey · MN DNR LakeFinder
EPA Impairment Status
Lost Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MN27-0103-00 · Official waterbody report
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
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate
Most recent sample: 2024-10-19
Monitoring stations: 1