French Lake
French Lake in Rice County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 1.7 ft visibility. Phosphorus: 134 µg/L. Chlorophyll-a (algae): 46.3 µg/L. Maximum depth: 56 ft. Surface area: 875.81 acres.
- Clarity
- 1.7 ft
- Typical in August
- 80°F
- Max depth
- 56 ft
- Area
- 876 acres
- Type
- Hypereutrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Mar 31
- Open water
- 246 days
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near French Lake →
Next lake in Rice County
Free interactive depth-contour map of French Lake, reaching a maximum surveyed depth of 50 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
French Lake is a 876-acre highly nutrient-loaded hypereutrophic lake in Rice County, Minnesota with a maximum depth of 56 feet. Water quality is graded F based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 16 documented fish species including black crappie, bluegill, and bowfin (dogfish). Public access is available with 1 public boat landing. Compared to the 13 other monitored lakes in Rice County, French Lake ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-16. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyBacteria A
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.
Based on E. coli testing, French Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 6 samples across 2 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Minnesota’s current beach and health-department advisories before swimming.
Water Quality Grade: F (Algae-prone)
Very murky, less than 1.7 ft of visibility. Phosphorus level: 134 µg/L. Chlorophyll-a: 46.3 µg/L. Trophic State Index: 71.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.7 ft | Not graded |
| Phosphorus | 134 µg/L | Poor |
| Chlorophyll-a (Algae) | 46.3 µg/L | Poor |
| Trophic State Index (TSI) | 71 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near French Lake
Compare lakeside cabins, hotels, and vacation rentals near French Lake in Rice 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around French Lake are listed below.
Top-rated places to stay near French Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
French Lake typically sits around 80°F at the surface in August. Summer average is about 74°F. Usually warmest in Aug (about 80°F) and coldest in May (about 65°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 112 field readings (2025–2025) via the EPA Water Quality Portal. See the full French Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 56 ft |
| Surface Area | 876 acres |
| Shoreline Length | 4.8 mi |
| Littoral Zone | 45% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- French LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing French 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.
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.19 m/yr | 2 |
| Phosphorus | ↑ Improving | -105.5 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +44.9 µg/L/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (26 observations).
Estimated open water season: 246 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-02 (2024) | 2018-04-30 (2018) |
| Ice-In | 1997-11-19 (1997) | 2024-01-04 (2024) |
Most recent ice-out: 2026-03-26
Reservoir Info (USACE NID)
French Lake is a man-made reservoir impounded by the French Lake (completed 1960), built primarily for recreation on the Cannon River-TR; other-type dam, 8 ft tall.
- Surface area
- 880 ac
- Normal storage
- 2,300 ac-ft
- Max storage
- 3,500 ac-ft
- Drainage area
- 6.4 sq mi
- Hazard class
- Low
- Owner
- County of Rice
Source: USACE National Inventory of Dams, NID ID MN01611 · Operator website
EPA Impairment Status
French 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 MN66-0038-00 · Official waterbody report
County Ranking
Ranked #9 of 14 lakes in Rice County
Nearby Lakes With Higher Grades
French Lake holds Grade F. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Rice County
Frequently asked questions about French Lake
What is the water quality grade for French Lake?
- French Lake in Rice County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 1.7 ft visibility. Phosphorus: 134 µg/L. Chlorophyll-a (algae): 46.3 µg/L. Maximum depth: 56 ft. Surface area: 875.81 acres.
Is French Lake safe to swim in?
- Based on E. coli testing, French Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 6 samples across 2 seasons. That works out to a bacteria swim-safety grade of A — a historical summary of past testing, not a current reading. French Lake has a water quality grade of F (Algae-prone). Bacteria levels can spike quickly after heavy rain, so always check Minnesota's current beach and health-department advisories before you swim.
What is the water temperature of French Lake?
- French Lake typically sits around 80°F at the surface in August, from 112 EPA Water Quality Portal field readings (2025–2025). That is a typical value for the month, not a live reading.
How deep is French Lake?
- French Lake has a maximum depth of 56 feet. The lake covers 875.81 acres.
What fish are in French Lake?
- Fish species found in French Lake include black crappie, bluegill, bowfin (dogfish), common carp, freshwater drum, hybrid crappie, hybrid sunfish, largemouth bass, muskellunge, northern pike, pumpkinseed, walleye, white bass, white crappie, yellow bullhead, yellow perch. French Lake is located in Rice County, Minnesota.
When does French Lake thaw?
- French Lake typically has ice-out around Mar 31. Ice typically forms around Dec 2. The open water season is approximately 246 days.
Are there boat ramps on French Lake?
- French Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include French Lake. Public access is listed as yes.
Explore French Lake across LakeGrade
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Species activity outlook by water temperature and season
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Very high nutrients, dense algae, poor clarity
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Where this data comes from
491 measurements from 9 monitoring stations, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA491 samples · 2024–2025
Analytical methods
- Field measurement/observation, generic method
- Turbidity, Nephelometric Method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (9)
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
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate