Long Lake
Long Lake in Hennepin County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 3.3 ft visibility. Phosphorus: 62 µg/L. Chlorophyll-a (algae): 32 µg/L. Maximum depth: 33 ft. Surface area: 284.99 acres.
- Clarity
- 3.3 ft
- Typical in August
- 67°F
- Max depth
- 33 ft
- Area
- 285 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Mar 31
- Open water
- 247 days
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Long Lake →
Next lake in Hennepin County
Long Lake is a 285-acre productive, nutrient-rich eutrophic lake in Hennepin County, Minnesota with a maximum depth of 33 feet. Water quality is graded F based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 14 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 80 other monitored lakes in Hennepin County, Long Lake ranks #58 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-13. 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.
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 3.3 ft of visibility. Phosphorus level: 62 µg/L. Chlorophyll-a: 32 µg/L. Trophic State Index: 63.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.3 ft | Not graded |
| Phosphorus | 62 µg/L | Poor |
| Chlorophyll-a (Algae) | 32 µg/L | Poor |
| Trophic State Index (TSI) | 63 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long Lake in Hennepin 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 Long Lake are listed below.
Top-rated places to stay near Long 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
Long Lake typically sits around 67°F at the surface in August. Summer average is about 65°F. Usually warmest in Aug (about 67°F) and coldest in Nov (about 46°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 860 field readings (2010–2025) via the EPA Water Quality Portal. See the full Long Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Long Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (654,636 cells/mL) on July 18, 2026.
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 | 33 ft |
| Surface Area | 285 acres |
| Shoreline Length | 3.9 mi |
| Littoral Zone | 46% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Nelson Lakeside ParkPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Long Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Fisheries Survey Summary
10 surveys on file from MN DNR Fisheries. Most recent: 2023-06-26 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 34.08 | 0.19 lb |
| Black Crappie | 16.69 | 0.21 lb |
| Black Bullhead | 13.21 | 0.58 lb |
| Largemouth Bass | 9.51 | 1.23 lb |
| Yellow Perch | 7.11 | 0.13 lb |
| Walleye | 2.83 | 1.95 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.
Bluegill
Black Crappie
Black Bullhead
Largemouth Bass
From the 2023-06-26 survey
Long Lake is a 285-acre lake with a maximum depth of 33 feet. The lake is located within the town of Long Lake, in central Hennepin County. Long is actively managed for Walleye and Northern Pike, with secondary emphasis on Largemouth Bass and Bluegill. Long also supports catchable populations of Black Crappie. The…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Long Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — LongFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — LongFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — LongPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.053 m/yr | 6 |
| Phosphorus | ↓ Declining | +6.93 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +2.96 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (31 observations).
Estimated open water season: 247 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-03 (2024) | 2018-05-02 (2018) |
| Ice-In | 2022-11-22 (2022) | 2015-12-19 (2015) |
Most recent ice-out: 2026-03-31
EPA Impairment Status
Long 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 MN27-0160-00 · Official waterbody report
County Ranking
Ranked #58 of 81 lakes in Hennepin County
Nearby Lakes With Higher Grades
Long Lake holds Grade F. 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 Hennepin County
Frequently asked questions about Long Lake
What is the water quality grade for Long Lake?
- Long Lake in Hennepin County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 3.3 ft visibility. Phosphorus: 62 µg/L. Chlorophyll-a (algae): 32 µg/L. Maximum depth: 33 ft. Surface area: 284.99 acres.
Is Long 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. Long Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 32 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Long Lake?
- Long Lake typically sits around 67°F at the surface in August, from 860 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Long Lake?
- Long Lake has a maximum depth of 33 feet. The lake covers 284.99 acres.
What fish are in Long Lake?
- Fish species found in Long Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, yellow bullhead, yellow perch. Long Lake is located in Hennepin County, Minnesota.
When does Long Lake thaw?
- Long Lake typically has ice-out around Mar 31. Ice typically forms around Dec 3. The open water season is approximately 247 days.
Does Long Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Long Lake (clouds, ice, or an off-season gap). The most recent reading was high (654,636 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Long Lake?
- Long Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Nelson Lakeside Park. Public access is listed as yes.
Explore Long Lake across LakeGrade
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Where this data comes from
207 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
MNPCA207 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
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