Frog Lake
Frog Lake in Lake County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10.5 ft visibility. Maximum depth: 38 ft. Surface area: 53.19 acres.
- Clarity
- 10.5 ft
- Max depth
- 38 ft
- Area
- 53 acres
- Trend
- ↑ Improving
- Public access
- No
Next lake in Lake County
Why Frog Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Frog Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Frog Lake is a 53-acre lake in Lake County, Minnesota with a maximum depth of 38 feet. Overall water quality is improving over recent sampling years. The lake supports 3 documented fish species including largemouth bass, northern pike, and yellow perch. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-06-11. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Frog Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Good clarity, visible to about 10.5 ft. Trophic State Index: 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Frog Lake
Compare lakeside cabins, hotels, and vacation rentals near Frog Lake in Lake County, Minnesota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Frog Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 38 ft |
| Surface Area | 53 acres |
| Shoreline Length | 1.8 mi |
| Littoral Zone | 40% |
| Public Access | No |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Frog Lake
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 2000-06-26 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Perch | 23.00 | 0.18 lb |
| Largemouth Bass | 9.00 | 1.31 lb |
| Northern Pike | 5.00 | 6.02 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.
Yellow Perch
Largemouth Bass
Northern Pike
From the 2000-06-26 survey
Frog Lake is in Ecological Lake Class 4, which consists of 47 lakes in northeast Minnesota that are small, deep, and have very clear and soft (unmineralized) water. Frog Lake differs from most of the lakes in this lake class in that it is shallower (38 ft) than the lake class average of 61 ft. Frog Lake ranks as…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Frog Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — FrogFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.129 m/yr | 5 |
EPA Impairment Status
Frog 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 MN38-0532-00 · Official waterbody report · Matched by proximity (2.01 km)
Nearby Lakes in Lake County
Frequently asked questions about Frog Lake
What is the water quality grade for Frog Lake?
- Frog Lake in Lake County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10.5 ft visibility. Maximum depth: 38 ft. Surface area: 53.19 acres.
Is Frog Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Frog Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
How deep is Frog Lake?
- Frog Lake has a maximum depth of 38 feet. The lake covers 53.19 acres.
What fish are in Frog Lake?
- Fish species found in Frog Lake include largemouth bass, northern pike, yellow perch. Frog Lake is located in Lake County, Minnesota.
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Where this data comes from
4 measurements from 1 monitoring station, 2023–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA4 samples · 2023–2025
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder