Florence Lake
Isanti County, Minnesota135 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Florence Lake. Here is what has been measured.
- 26 ft max depth
- Public access
- Limited data
Florence Lake in Isanti County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 8.9 ft visibility. Maximum depth: 26 ft. Surface area: 135.45 acres.
Minnesota DNR's Targeted Survey on July 14, 2025 caught 27.26 largemouth bass per hour of electrofishing at Florence Lake. Length samples in the latest survey that recorded them ran 2–16 inches. DNR survey details →
Florence Lake is a 135-acre lake in Isanti County, Minnesota with a maximum depth of 26 feet. Overall water quality is declining over recent sampling years. The lake supports 15 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-29. Methodology: how these readings are compared.
What Florence Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing15 species recorded
- Ice seasonIce-out around Apr 3
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Florence 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 Florence Lake
These are the measurements Minnesota PCA publishes for Florence 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 8.9 ft. TSI 46.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 8.9ft | 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. | 46 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Florence Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Florence Lake typically sits around 56°F at the surface in October. Summer average is about 76°F. Usually warmest in Jul (about 78°F) and coldest in Apr (about 52°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (52°F) to its warmest (78°F).
Typical surface water temperature by month, from 48 field readings (2024–2025) via the EPA Water Quality Portal. See the full Florence Lake water temperature breakdown →
Minnesota DNR's Targeted Survey on July 14, 2025 caught 27.26 largemouth bass per hour of electrofishing at Florence Lake. Length samples in the latest survey that recorded them ran 2–16 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Florence Lake’s water-quality measurements separately, and the water-quality trend over 6 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: 2025-07-14 (Targeted Survey).
7 surveys on file · most recent 2025-07-14 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Black Bullhead | 41.94 | 6–11 in 2025-06-02 | 0.23 lb |
| Bluegill | 29.78 | 3–9 in 2025-06-02 | 0.16 lb |
| Largemouth Bass | 18.98 | 2–16 in 2025-06-02 | 0.68 lb |
| Pumpkinseed | 9.47 | 3–7 in 2025-06-02 | 0.13 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.
Black Bullhead
Bluegill
Largemouth Bass
Pumpkinseed
From the 2025-07-14 survey
A targeted survey of the nearshore fish community was conducted by Hinckley fisheries staff on Florence Lake on July 14, 2025. Nearshore sampling captured 15 species of fish: Banded Kilifish, Blacknose Shiner, Bluegill, Bowfin, Central Mudminnow, Golden Shiner, Green Sunfish, Hybrid Sunfish, Iowa Darter, Largemouth…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Florence Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — FlorenceFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Florence (1841)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — FlorenceFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — FlorencePublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
26 ft
Surface area
135 acres
Shoreline
2.2 mi
Littoral zone
94%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
15 sq mi
HydroLAKES / HydroSHEDS
Elevation
935 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Florence LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Florence Lake
Compare lakeside cabins, hotels, and vacation rentals near Florence 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.
Top-rated places to stay near Florence Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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 →
Follow Florence Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fish Species
Click a species to see every lake where it is documented.
Fishing Florence Lake
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Ice season
Typical ice-out
Apr 3
Earliest Mar 2, 2024 · Latest May 2, 2013
Typical ice-in
Nov 26
Earliest Nov 5, 2019 · Latest Dec 19, 2015
Most recent ice-out
Mar 18
2025
47 observations · Minnesota PCA ice records
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Florence Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 2 facilities have a reported Clean Water Act violation in the past three years.
- Cambridge WwtpCambridge · 1.7 mi away · NPDES MN0020362MajorRecent violation
- Isanti WwtpIsanti · 3.1 mi away · NPDES MN0023795Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Isanti County
Frequently asked questions about Florence Lake
Where is Florence Lake?
- Florence Lake is a lake in Isanti County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Florence Lake?
- Florence Lake in Isanti County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 8.9 ft visibility. Maximum depth: 26 ft. Surface area: 135.45 acres.
Is Florence Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Florence Lake?
- Florence Lake typically sits around 56°F at the surface in October, from 48 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Florence Lake?
- Florence Lake has a maximum depth of 26 feet. The lake covers 135.45 acres.
What fish are in Florence Lake?
- Fish species found in Florence Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white sucker, yellow bullhead, yellow perch. Florence Lake is located in Isanti County, Minnesota.
What did the DNR fisheries survey find at Florence Lake?
- Minnesota DNR's Targeted Survey on July 14, 2025 caught 27.26 largemouth bass per hour of electrofishing at Florence Lake. Length samples in the latest survey that recorded them ran 2–16 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Florence Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
When does Florence Lake thaw?
- Florence Lake typically has ice-out around Apr 3. Ice typically forms around Nov 26. The open water season is approximately 237 days.
Are there boat ramps on Florence Lake?
- Florence Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Florence Lake. Public access is listed as yes.
Can I fish at Florence Lake?
- Florence Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. 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 Florence Lake across LakeQuality
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in Isanti County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the Rum River Watershed, ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
More lakes in Minnesota
State Parks Near Florence Lake
Other Lakes in Minnesota
Mesotrophic Lakes in Minnesota
Where this data comes from
165 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA165 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (1)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
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