Francis Lake
Francis Lake in Isanti County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2 ft visibility. Phosphorus: 159 µg/L. Chlorophyll-a (algae): 56.1 µg/L. Maximum depth: 7 ft. Surface area: 269.43 acres.
- Clarity
- 2 ft
- Typical in August
- 74°F
- Max depth
- 7 ft
- Area
- 269 acres
- Type
- Hypereutrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 11
- Open water
- 219 days
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Francis Lake →
Next lake in Isanti County
Francis Lake is a 269-acre highly nutrient-loaded hypereutrophic lake in Isanti County, Minnesota with a maximum depth of 7 feet (4-foot average). Water quality is graded F based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. The lake supports 14 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 3 public boat landings. Compared to the 16 other monitored lakes in Isanti County, Francis Lake ranks #15 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-05. 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.
Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom
Water Quality Grade: F (Algae-prone)
Very murky, less than 2 ft of visibility. Phosphorus level: 159 µg/L. Chlorophyll-a: 56.1 µg/L. Trophic State Index: 71.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | Not graded |
| Phosphorus | 159 µg/L | Poor |
| Chlorophyll-a (Algae) | 56.1 µg/L | Poor |
| Trophic State Index (TSI) | 71 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Francis Lake
Compare lakeside cabins, hotels, and vacation rentals near Francis Lake in Isanti 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 Francis Lake are listed below.
Top-rated places to stay near Francis Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Francis Lake typically sits around 74°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 76°F) and coldest in Jun (about 72°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 11 field readings (2018–2024) via the EPA Water Quality Portal. See the full Francis Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 7 ft |
| Average Depth | 4 ft |
| Surface Area | 269 acres |
| Shoreline Length | 3.8 mi |
| Littoral Zone | 100% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Long Lake (Northeast)Public
- Long Lake (West)Public
- Francis LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Francis Lake
DNR Fisheries Survey Summary
6 surveys on file from MN DNR Fisheries. Most recent: 2024-06-19 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Perch | 96.82 | 0.15 lb |
| Black Bullhead | 59.72 | 0.24 lb |
| Black Crappie | 35.48 | 0.27 lb |
| OTS | 12.00 | 1.25 lb |
| Largemouth Bass | 9.81 | 1.65 lb |
| Bluegill | 8.11 | 0.27 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.
Yellow Perch
Black Bullhead
Black Crappie
Largemouth Bass
From the 2024-06-19 survey
A survey of nearshore fish species was conducted on Francis Lake on June 19, 2024 by Hinckley fisheries staff. Ten sampling sites were evenly spaced around the shoreline and each site was sampled by electrofishing, and/or seining. Nearshore sampling captured 17 species of fish: Bluegill, Black Crappie, Largemouth…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Francis Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — FrancisFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Francis (1848)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — FrancisFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — FrancisPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.253 m/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (22 observations).
Estimated open water season: 219 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-03 (2024) | 2013-05-05 (2013) |
| Ice-In | 2006-11-07 (2006) | 2007-11-24 (2007) |
Most recent ice-out: 2026-03-31
EPA Impairment Status
Francis Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN30-0080-00 · Official waterbody report
County Ranking
Ranked #15 of 17 lakes in Isanti County
Nearby Lakes With Higher Grades
Francis Lake holds Grade F. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Isanti County
Frequently asked questions about Francis Lake
What is the water quality grade for Francis Lake?
- Francis Lake in Isanti County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2 ft visibility. Phosphorus: 159 µg/L. Chlorophyll-a (algae): 56.1 µg/L. Maximum depth: 7 ft. Surface area: 269.43 acres.
Is Francis Lake safe to swim in?
- Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. Francis Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 56.1 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Francis Lake?
- Francis Lake typically sits around 74°F at the surface in August, from 11 EPA Water Quality Portal field readings (2018–2024). That is a typical value for the month, not a live reading.
How deep is Francis Lake?
- Francis Lake has a maximum depth of 7 feet and an average depth of 4 feet. The lake covers 269.43 acres.
What fish are in Francis Lake?
- Fish species found in Francis Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, white sucker, yellow bullhead, yellow perch. Francis Lake is located in Isanti County, Minnesota.
When does Francis Lake thaw?
- Francis Lake typically has ice-out around Apr 11. Ice typically forms around Nov 16. The open water season is approximately 219 days.
Are there boat ramps on Francis Lake?
- Francis Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Long Lake (Northeast), Long Lake (West), Francis Lake. Public access is listed as yes.
Explore Francis Lake across LakeGrade
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Species activity outlook by water temperature and season
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Where this data comes from
64 measurements from 2 monitoring stations, 2021–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA64 samples · 2021–2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate