Parent Lake
Lake County, MinnesotaLimited DataOligotrophic
Parent Lake earns an A — every scored parameter (clarity) rates among the best monitored waters in Lake County.
A TSI value of 32 puts Parent Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's 50 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. Parent Lake covers 451 acres alongside 4.7 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Among the 142 graded lakes in Lake County, Parent Lake ranks 24 — in the top quartile locally.
Parent Lake has no invasive species recorded in Minnesota state databases as of 2021, though prevention practices still apply at all access points. Walleye are documented at Parent Lake, one of 9 fish species on record for the lake. No formal public access is documented at Parent 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 2021-06-18. Grade methodology: LakeGrade methodology.
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 23 ft down. Trophic State Index: 32.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 23 ft | A |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 32 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 50 ft |
| Surface Area | 450.97 acres |
| Shoreline Length | 4.7 mi |
| Littoral Zone | 20% |
| Public Access | No |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Parent Lake (14-day solunar calendar)
→ Is it safe to eat fish from Parent Lake? (mercury & PFAS guide)
→ Parent Lake fishing regulations (limits, seasons, special rules)
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.274 m/yr | 4 |
Location
County Ranking
Ranked #24 of 142 lakes in Lake County
Nearby Lakes in Lake County
More Minnesota Lake Rankings
Other Grade A Lakes in Minnesota
Oligotrophic Lakes in Minnesota
Compare Parent Lake With Nearby Lakes
DNR Fisheries Survey Summary
11 surveys on file from MN DNR Fisheries. Most recent: 2025-07-30 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| CIS | 16.33 | 0.23 lb |
| Tullibee (Cisco) | 11.12 | 0.2 lb |
| White Sucker | 5.00 | 2.89 lb |
| Rock Bass | 4.35 | 0.19 lb |
| Smallmouth Bass | 1.98 | 1.03 lb |
| Walleye | 1.14 | 5.18 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.
CIS
Tullibee (Cisco)
White Sucker
Rock Bass
From the 2025-07-30 survey
Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Parent Lake on July 30th, 2025, to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Cisco, also known as Tullibee, the most sensitive coldwater species present in this lake.…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Parent Lake. 2 reports on file.
- —Fisheries Lake Survey — ParentFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — ParentFish Stocking History · MN DNR LakeFinder
EPA Impairment Status
Parent 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 MN38-0526-00 · 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
Most recent sample: 2021-06-18
Monitoring stations: 1