Lac la Croix Lake
Lac la Croix Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8 ft visibility. Maximum depth: 168 ft. Surface area: 29596.66 acres.
- Clarity
- 8 ft
- Max depth
- 168 ft
- Area
- 29,597 acres
- Trend
- ↓ Declining
- Public access
- No
Next lake in St. Louis County
Why Lac la Croix 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 Lac la Croix 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.
Lac la Croix Lake is a 29,597-acre lake in St. Louis County, Minnesota with a maximum depth of 168 feet. Overall water quality is declining over recent sampling years. The lake supports 12 documented fish species including burbot, lake trout, and lake whitefish. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-07-27. 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 Lac la Croix Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Moderate clarity, visible to about 8 ft. Trophic State Index: 47.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Lac la Croix Lake
Compare lakeside cabins, hotels, and vacation rentals near Lac la Croix Lake in St. Louis 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 Lac la Croix Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 168 ft |
| Surface Area | 29,597 acres |
| Shoreline Length | 482.4 mi |
| Littoral Zone | 29% |
| 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 Lac la Croix Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Fisheries Survey Summary
7 surveys on file from MN DNR Fisheries. Most recent: 2025-07-31 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Tullibee (Cisco) | 15.67 | 0.34 lb |
| RBS | 8.40 | 0.03 lb |
| CIS | 7.86 | 0.3 lb |
| Walleye | 6.24 | 1.81 lb |
| LKW | 1.80 | 1.73 lb |
| Rock Bass | 1.73 | 0.22 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.
Tullibee (Cisco)
RBS
CIS
Walleye
From the 2025-07-31 survey
Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Lac la Croix on July 31st, 2025, 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 (Lake Whitefish and…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Lac la Croix Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Lac la CroixFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.307 m/yr | 3 |
EPA Impairment Status
Lac la Croix 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 MN69-0224-00 · Official waterbody report
Nearby Lakes in St. Louis County
Frequently asked questions about Lac la Croix Lake
What is the water quality grade for Lac la Croix Lake?
- Lac la Croix Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8 ft visibility. Maximum depth: 168 ft. Surface area: 29596.66 acres.
Is Lac la Croix Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Lac la Croix 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 Lac la Croix Lake?
- Lac la Croix Lake has a maximum depth of 168 feet. The lake covers 29596.66 acres.
What fish are in Lac la Croix Lake?
- Fish species found in Lac la Croix Lake include burbot, lake trout, lake whitefish, northern pike, rainbow smelt, rock bass, sauger, smallmouth bass, tullibee (cisco), walleye, white sucker, yellow perch. Lac la Croix Lake is located in St. Louis County, Minnesota.
Explore Lac la Croix Lake across LakeGrade
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Where this data comes from
6 measurements from 2 monitoring stations, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA6 samples · 2021–2025
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (2)
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