Topaz Lake
Topaz Lake in Lake County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 17.6 ft visibility. Maximum depth: 110 ft. Surface area: 409.8 acres.
- Clarity
- 17.6 ft
- Max depth
- 110 ft
- Area
- 410 acres
- Trend
- → Stable
- Public access
- No
Next lake in Lake County
Why Topaz 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 Topaz 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.
Topaz Lake is a 410-acre lake in Lake County, Minnesota with a maximum depth of 110 feet. The lake supports 4 documented fish species including burbot, cisco species, and lake trout. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-07-19. 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 Topaz Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Crystal clear, you can see 17.6 ft down. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 17.6 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Topaz Lake
Compare lakeside cabins, hotels, and vacation rentals near Topaz 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 Topaz Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 110 ft |
| Surface Area | 410 acres |
| Shoreline Length | 10.1 mi |
| Littoral Zone | 26% |
| 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 Topaz Lake
DNR Fisheries Survey Summary
4 surveys on file from MN DNR Fisheries. Most recent: 2025-08-01 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Tullibee (Cisco) | 37.52 | 0.32 lb |
| CIS | 32.70 | 0.27 lb |
| BUB | 2.67 | 1.21 lb |
| Lake Trout | 1.27 | 6.04 lb |
| Smallmouth Bass | 0.80 | 0.21 lb |
| Walleye | 0.67 | 2.38 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
BUB
Lake Trout
Smallmouth Bass
From the 2025-08-01 survey
Temperature and dissolved oxygen measurements were collected from the deepest basin in Amoeber Lake on August 1st, 2025. This was done to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Lake Trout, the most sensitive coldwater species present in this lake (Cisco,…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Topaz Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — AmoeberFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.103 m/yr | 5 |
EPA Impairment Status
Topaz 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 MN38-0166-00 · Official waterbody report · Matched by proximity (1.64 km)
Nearby Lakes in Lake County
Frequently asked questions about Topaz Lake
What is the water quality grade for Topaz Lake?
- Topaz Lake in Lake County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 17.6 ft visibility. Maximum depth: 110 ft. Surface area: 409.8 acres.
Is Topaz Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Topaz 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 Topaz Lake?
- Topaz Lake has a maximum depth of 110 feet. The lake covers 409.8 acres.
What fish are in Topaz Lake?
- Fish species found in Topaz Lake include burbot, cisco species, lake trout, smallmouth bass. Topaz Lake is located in Lake County, Minnesota.
Explore Topaz Lake across LakeGrade
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Where this data comes from
10 measurements from 5 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA10 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (5)
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