Hart Lake
Hubbard County, Minnesota226 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Hart Lake. Here is what has been measured.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 13 ft max depth
- Public access
Hart Lake in Hubbard County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.5 ft visibility. Phosphorus: 45.5 µg/L. Chlorophyll-a (algae): 9.8 µg/L. Maximum depth: 13 ft. Surface area: 226.31 acres.
Minnesota DNR's Standard Survey on July 14, 1977 caught 1.00 walleye per gill net at Hart Lake. DNR survey details →
Hart Lake is a 226-acre productive, nutrient-rich eutrophic lake in Hubbard County, Minnesota with a maximum depth of 13 feet. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 67 other monitored lakes in Hubbard County, Hart Lake ranks #68 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-09-28. Methodology: how these readings are compared.
What Hart Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyRecreation use not supported
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. Hart Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Hart 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 Hart Lake
These are the measurements Minnesota PCA publishes for Hart 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 4.5 ft. Phosphorus 45.5 µg/L. Chlorophyll-a 9.8 µg/L. TSI 56.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 45.5µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 9.8µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 56 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Hart Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Hart Lake typically sits around 63°F at the surface in September. Summer average is about 71°F. Usually warmest in Aug (about 72°F) and coldest in May (about 62°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (62°F) to its warmest (72°F).
Typical surface water temperature by month, from 28 field readings (2018–2023) via the EPA Water Quality Portal. See the full Hart Lake water temperature breakdown →
Minnesota DNR's Standard Survey on July 14, 1977 caught 1.00 walleye per gill net at Hart Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Hart Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 1977-07-14 (Standard Survey).
1 survey on file · most recent 1977-07-14 (Standard Survey)
49 years old| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Black Bullhead | 79.13 | 0.66 lb | |
| Yellow Perch | 9.38 | 0.51 lb | |
| White Sucker | 1.63 | 1.6 lb | |
| Northern Pike | 1.13 | 1.29 lb | |
| Walleye | 1.00 | 1.9 lb | |
| Pumpkinseed | 0.75 | 0.2 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.
From the 1977-07-14 survey
Mostly Bullheads. Bullheads and Yellow Perch higher than statewide average in the net catch. Northern Pike, Walleye and Panfish lower.
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Hart Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — HartFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Hart (1255)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — HartPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
13 ft
Surface area
226 acres
Shoreline
2.6 mi
Littoral zone
100%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
65 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,289 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Hart 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 Hart Lake
Compare lakeside cabins, hotels, and vacation rentals near Hart Lake in Hubbard 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Hart Lake are listed below.
Top-rated places to stay near Hart 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 Hart Lake’s readings
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Fishing Hart Lake
Water quality readings over time
2 seasons of samples on record (2020–2023). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening2 years
Phosphorus
Worsening+2.17 µg/L/yr2 years
Chlorophyll-a
Improving-0.27 µg/L/yr2 years
EPA Impairment Status
Hart Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Recreation.
Source: EPA ATTAINS assessment unit MN29-0063-00 · Official waterbody report
Nearby Lakes in Hubbard County
Frequently asked questions about Hart Lake
Where is Hart Lake?
- Hart Lake is a lake in Hubbard County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Hart Lake?
- Hart Lake in Hubbard County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.5 ft visibility. Phosphorus: 45.5 µg/L. Chlorophyll-a (algae): 9.8 µg/L. Maximum depth: 13 ft. Surface area: 226.31 acres.
Is Hart Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Hart Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Hart Lake?
- Hart Lake typically sits around 63°F at the surface in September, from 28 EPA Water Quality Portal field readings (2018–2023). That is a typical value for the month, not a live reading.
How deep is Hart Lake?
- Hart Lake has a maximum depth of 13 feet. The lake covers 226.31 acres.
What did the DNR fisheries survey find at Hart Lake?
- Minnesota DNR's Standard Survey on July 14, 1977 caught 1.00 walleye per gill net at Hart Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Hart Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Hart Lake?
- Hart Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Hart Lake. Public access is listed as yes.
Can I fish at Hart Lake?
- Hart 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 Hart Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
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Fish species and best lakes in Hubbard County
Species activity outlook by water temperature and season
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Where to stay at Minnesota's top lakes, each with its readings
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Where this data comes from
45 measurements from 1 monitoring station, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA45 samples · 2020–2023
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent 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
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