Lac Lake
Lac Lake in Carlton County, Minnesota has a water quality grade of C (Fair). Water clarity: 9.5 ft visibility. Phosphorus: 108 µg/L. Chlorophyll-a (algae): 5.5 µg/L.
- Clarity
- 9.5 ft
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- No
Next lake in Carlton County
Lac Lake is a productive, nutrient-rich eutrophic lake in Carlton County, Minnesota. Water quality is graded C based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 21 other monitored lakes in Carlton County, Lac Lake ranks #11 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-07-01. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Moderate clarity, visible to about 9.5 ft. Phosphorus level: 108 µg/L. Chlorophyll-a: 5.5 µg/L. Trophic State Index: 55.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9.5 ft | Not graded |
| Phosphorus | 108 µg/L | Poor |
| Chlorophyll-a (Algae) | 5.5 µg/L | Good |
| Trophic State Index (TSI) | 55 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Lac Lake
Compare lakeside cabins, hotels, and vacation rentals near Lac Lake in Carlton 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 Lake
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Fishing Lac Lake
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Lac Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Aquatic Plant Report — Lac (0262)Aquatic Plant Report · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.941 m/yr | 5 |
| Phosphorus | ↓ Declining | +55.85 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -0.98 µg/L/yr | 5 |
EPA Impairment Status
Lac Lake is officially listed as impaired under Clean Water Act §303(d) in the 2019 EPA reporting cycle.
Causes of impairment
Source: EPA ATTAINS assessment unit FDL_109 · Official waterbody report
County Ranking
Ranked #11 of 22 lakes in Carlton County
Nearby Lakes With Higher Grades
Lac Lake holds Grade C. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Carlton County
Frequently asked questions about Lac Lake
What is the water quality grade for Lac Lake?
- Lac Lake in Carlton County, Minnesota has a water quality grade of C (Fair). Water clarity: 9.5 ft visibility. Phosphorus: 108 µg/L. Chlorophyll-a (algae): 5.5 µg/L.
Is Lac Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Lac Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 5.5 µg/L. Always check local health department advisories before swimming.
Explore Lac Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Carlton County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Lake Superior Basin (MN+WI), ranked by water quality
High nutrients, frequent algae, reduced clarity
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Lac Lake
Other Grade C Lakes in Minnesota
Eutrophic Lakes in Minnesota
Where this data comes from
57 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Fond du Lac Band of Chippewa (MN)
FONDULAC_WQX57 samples · 2020–2024
Analytical methods
- Phosphorus by Two Reagent Colorimetry
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
- 10200 H ~ Chlorophyll a-b-c Determination
- Color, APHA Platinum-Cobalt
- For determination of Copper by the Bicinchoninate 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