Hoffman Lake
Isanti County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Hoffman Lake. Here is what has been measured.
- Mesotrophic
- 28 ft max depth
Hoffman Lake in Isanti County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3.7 ft visibility. Phosphorus: 15 µg/L. Chlorophyll-a (algae): 3.6 µg/L.
Hoffman Lake is a mesotrophic lake in Isanti County, Minnesota with an estimated average depth of about 28 feet. Overall water quality is declining over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 16 other monitored lakes in Isanti County, Hoffman Lake ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-29. Methodology: how these readings are compared.
For a place on the water, look through cabin and lake-house rentals near Hoffman Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Hoffman 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 Hoffman Lake
These are the measurements Minnesota PCA publishes for Hoffman Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 3.7 ft. Phosphorus 15 µg/L. Chlorophyll-a 3.6 µg/L. TSI 48.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.7ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 15µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 3.6µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 48 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Hoffman Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Hoffman Lake typically sits around 67°F at the surface in September. Summer average is about 76°F. Usually warmest in Jul (about 77°F) and coldest in May (about 65°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (65°F) to its warmest (77°F).
Typical surface water temperature by month, from 39 field readings (2017–2025) via the EPA Water Quality Portal. See the full Hoffman Lake water temperature breakdown →
Lake Details
Max depth
~28 ft est.
Public access
No
Listed by Minnesota PCA
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for Hoffman Lake.
Lake Size & Watershed
Watershed (drainage) area
0 sq mi
HydroLAKES / HydroSHEDS
Surface area
42 acres
HydroLAKES / HydroSHEDS
Shoreline
1 mi
HydroLAKES / HydroSHEDS
Elevation
892 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Stays via Stay22
Stays near Hoffman Lake
Compare lakeside cabins, hotels, and vacation rentals near Hoffman 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 Hoffman Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Fishing Hoffman Lake
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Worsening+2.16 µg/L/yr6 years
Chlorophyll-a
Worsening+0.26 µg/L/yr6 years
Nearby Lakes in Isanti County
Frequently asked questions about Hoffman Lake
Where is Hoffman Lake?
- Hoffman 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 Hoffman Lake?
- Hoffman Lake in Isanti County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3.7 ft visibility. Phosphorus: 15 µg/L. Chlorophyll-a (algae): 3.6 µg/L.
Is Hoffman 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 Hoffman Lake?
- Hoffman Lake typically sits around 67°F at the surface in September, from 39 EPA Water Quality Portal field readings (2017–2025). That is a typical value for the month, not a live reading.
How deep is Hoffman Lake?
- No published bathymetric survey covers Hoffman Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 28 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Can I fish at Hoffman Lake?
- Public access to Hoffman Lake is listed as no on the lake record, so confirm before you make the trip. 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 Hoffman Lake across LakeQuality
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Where this data comes from
88 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
MNPCA88 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder