Mirror Lake
Itasca County, MinnesotaOligotrophic
On the LakeGrade rubric, Mirror Lake pulls an A: clarity at 18.0 ft and 10 µg/L of phosphorus put it in the top bracket for Minnesota. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.
A TSI value of 36 puts Mirror Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. Mirror Lake reaches 45 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Mirror Lake covers 109 acres alongside 1.9 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Among the 141 graded lakes in Itasca County, Mirror Lake ranks 24 — in the top quartile locally.
No invasive species are currently listed at Mirror Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye alongside the lake's other 8 documented species — a notable draw for Minnesota anglers. A documented public access point at Mirror Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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 2023-09-18. Grade methodology: LakeGrade methodology.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 18 ft down. Phosphorus level: 10 µg/L. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 18 ft | A |
| Phosphorus | 10 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 45 ft |
| Surface Area | 109.11 acres |
| Shoreline Length | 1.9 mi |
| Littoral Zone | 44% |
| Public Access | Yes |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Mirror Lake (14-day solunar calendar)
→ Is it safe to eat fish from Mirror Lake? (mercury & PFAS guide)
→ Mirror Lake fishing regulations (limits, seasons, special rules)
Water Quality Trend: ↓ Declining
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.057 m/yr | 3 |
| Phosphorus | ↓ Declining | +1.46 µg/L/yr | 3 |
Location
County Ranking
Ranked #24 of 141 lakes in Itasca County
Nearby Lakes in Itasca County
More Minnesota Lake Rankings
State Parks Near Mirror Lake
Other Grade A Lakes in Minnesota
Oligotrophic Lakes in Minnesota
DNR Fisheries Survey Summary
9 surveys on file from MN DNR Fisheries. Most recent: 2022-07-25 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 34.80 | 0.14 lb |
| Yellow Perch | 18.01 | 0.15 lb |
| Largemouth Bass | 8.54 | 0.65 lb |
| GOS | 7.98 | 0.07 lb |
| Northern Pike | 5.72 | 2.24 lb |
| Rock Bass | 5.69 | 0.29 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Bluegill
Yellow Perch
Largemouth Bass
GOS
From the 2022-07-25 survey
A targeted survey of nearshore fish species in Mirror Lake was conducted on July 25th, 2022 by Index of Biological Integrity (IBI) Program Staff. Sampling sites were evenly spaced around the lake and each was sampled by backpack electrofishing and seining with a 50-foot or 15-foot seine, where possible. Backpack…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Mirror Lake. 3 reports on file.
- —Fisheries Lake Survey — MirrorFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Mirror (0641)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — MirrorPublic Water Access Sites · MN DNR LakeFinder
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Lake details from Minnesota DNR LakeFinder
Most recent sample: 2023-09-18
Monitoring stations: 1