Fremont Lake
Fremont Lake in Sherburne County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 3 ft visibility. Phosphorus: 40 µg/L. Chlorophyll-a (algae): 17.3 µg/L. Maximum depth: 8 ft. Surface area: 493 acres.
- Clarity
- 3 ft
- Typical in August
- 76°F
- Max depth
- 8 ft
- Area
- 493 acres
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 2
- Open water
- 242 days
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Fremont Lake →
Next lake in Sherburne County
Fremont Lake is a 493-acre productive, nutrient-rich eutrophic lake in Sherburne County, Minnesota with a maximum depth of 8 feet (5-foot average). Water quality is graded D based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 17 other monitored lakes in Sherburne County, Fremont Lake ranks #11 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-08. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyAlgae risk
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.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 3 ft of visibility. Phosphorus level: 40 µg/L. Chlorophyll-a: 17.3 µg/L. Trophic State Index: 59.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 40 µg/L | Fair |
| Chlorophyll-a (Algae) | 17.3 µg/L | Poor |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Fremont Lake
Compare lakeside cabins, hotels, and vacation rentals near Fremont Lake in Sherburne 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 Fremont Lake are listed below.
Top-rated places to stay near Fremont Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Fremont Lake typically sits around 76°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 79°F) and coldest in Feb (about 36°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 69 field readings (2019–2025) via the EPA Water Quality Portal. See the full Fremont Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Fremont Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (33,113 cells/mL) on November 22, 2025.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 8 ft |
| Average Depth | 5.2 ft |
| Surface Area | 493 acres |
| Shoreline Length | 5.3 mi |
| Littoral Zone | 100% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Lake FremontPublic
Fishing Fremont Lake
DNR Fisheries Survey Summary
4 surveys on file from MN DNR Fisheries. Most recent: 2008-06-09 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 92.53 | 0.17 lb |
| GOS | 41.85 | 0.07 lb |
| Hybrid Sunfish | 11.64 | 0.1 lb |
| Bluegill | 10.75 | 0.23 lb |
| Largemouth Bass | 9.27 | 1.91 lb |
| Brown Bullhead | 8.77 | 0.24 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.
Black Bullhead
GOS
Bluegill
Largemouth Bass
From the 2008-06-09 survey
Fremont Lake is a general development lake located in northeast Sherburne County, near Zimmerman. The lake is shallow, mostly 6-7 feet, with low to moderate water clarity (secchi depth 3.7 feet). Dissolved oxygen was adequate throughout the water column. These conditions are favorable for widespread aquatic plant…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Fremont Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — FremontFisheries Lake Survey · MN DNR LakeFinder
- —Public Water Access Sites — FremontPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.029 m/yr | 3 |
| Phosphorus | ↑ Improving | -6.5 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -3.48 µg/L/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (16 observations).
Estimated open water season: 242 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2017-03-07 (2017) | 2018-04-30 (2018) |
| Ice-In | 2007-11-24 (2007) | 2017-12-09 (2017) |
Most recent ice-out: 2026-03-26
EPA Impairment Status
Fremont 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 MN71-0016-00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Fremont Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Zimmerman WwtpZimmerman · 1.8 mi away · NPDES MN0042331Recent 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.
County Ranking
Ranked #11 of 18 lakes in Sherburne County
Nearby Lakes With Higher Grades
Fremont Lake holds Grade D. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Sherburne County
Frequently asked questions about Fremont Lake
What is the water quality grade for Fremont Lake?
- Fremont Lake in Sherburne County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 3 ft visibility. Phosphorus: 40 µg/L. Chlorophyll-a (algae): 17.3 µg/L. Maximum depth: 8 ft. Surface area: 493 acres.
Is Fremont Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Fremont Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 17.3 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Fremont Lake?
- Fremont Lake typically sits around 76°F at the surface in August, from 69 EPA Water Quality Portal field readings (2019–2025). That is a typical value for the month, not a live reading.
How deep is Fremont Lake?
- Fremont Lake has a maximum depth of 8 feet and an average depth of 5.2 feet. The lake covers 493 acres.
When does Fremont Lake thaw?
- Fremont Lake typically has ice-out around Apr 2. Ice typically forms around Nov 30. The open water season is approximately 242 days.
Does Fremont Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Fremont Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (33,113 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Fremont Lake?
- Fremont Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lake Fremont. Public access is listed as yes.
Explore Fremont Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Sherburne County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
Minnesota's cleanest and most-polluted lakes, ranked
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Where this data comes from
79 measurements from 4 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA79 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity by Nephelometry
Monitoring station identifiers (4)
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
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