Lac la Croix Lake
St. Louis County, Minnesota29,597 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Lac la Croix Lake. Here is what has been measured.
- Impaired · Mercury
- spiny waterflea
- 168 ft max depth
- Limited data
Lac la Croix Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 8 ft visibility. Maximum depth: 168 ft. Surface area: 29596.66 acres.
Minnesota DNR's Standard Survey on June 23, 2025 caught 9.07 walleye per gill net at Lac la Croix Lake. Length samples in the latest survey that recorded them ran 6–28 inches. DNR survey details →
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. Methodology: how these readings are compared.
What Lac la Croix Lake is good for
From access and monitoring records, not editorial picks.
- Fishing12 species recorded
- Deep water168 ft surveyed max depth
- Big water29,597 acres
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Lac la Croix Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Whether Lac la Croix Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lac la Croix Lake
These are the measurements Minnesota PCA publishes for Lac la Croix Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 8 ft. TSI 47.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 47 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Lac la Croix Lake
Answers come straight from the public measurements and survey records on this page.
Minnesota DNR's Standard Survey on June 23, 2025 caught 9.07 walleye per gill net at Lac la Croix Lake. Length samples in the latest survey that recorded them ran 6–28 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Lac la Croix Lake’s water-quality measurements separately, and the water-quality trend over 3 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
7 surveys on file from MN DNR Fisheries. Most recent: 2025-07-31 (Targeted Survey).
7 surveys on file · most recent 2025-07-31 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Tullibee (Cisco) | 15.67 | 3–21 in 2025-06-23 | 0.34 lb |
| Walleye | 6.24 | 6–28 in 2025-06-23 | 1.81 lb |
| Rock Bass | 1.73 | 3–8 in 2025-06-23 | 0.22 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
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)
Walleye
Rock Bass
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
Lake Details
Max depth
168 ft
Surface area
29,597 acres
Shoreline
482.4 mi
Littoral zone
29%
Share shallower than 15 ft
Public access
No
Listed by Minnesota PCA
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Stays near Lac la Croix Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Lac la Croix Lake
- → Lac la Croix Lake fishing: DNR survey catch rates, species & stocking
- → Lac la Croix Lake fishing forecast & best times (species outlook + 14-day solunar calendar)
- → Lac la Croix Lake fishing regulations (limits, seasons, special rules)
- → Is it safe to eat fish from Lac la Croix Lake? (mercury & PFAS guide)
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water quality readings over time
3 seasons of samples on record (2021–2025). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening3 years
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
Designated uses not supporting: Fish consumption.
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
Where is Lac la Croix Lake?
- Lac la Croix Lake is a lake in St. Louis County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Lac la Croix Lake?
- Lac la Croix Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 8 ft visibility. Maximum depth: 168 ft. Surface area: 29596.66 acres.
Is Lac la Croix Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lac la Croix Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
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.
What did the DNR fisheries survey find at Lac la Croix Lake?
- Minnesota DNR's Standard Survey on June 23, 2025 caught 9.07 walleye per gill net at Lac la Croix Lake. Length samples in the latest survey that recorded them ran 6–28 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Lac la Croix Lake’s water-quality measurements separately, and the water-quality trend over 3 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Lac la Croix Lake?
- Public access to Lac la Croix Lake is listed as no on the lake record, so confirm before you make the trip. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Lac la Croix Lake across LakeQuality
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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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake details from Minnesota DNR LakeFinder