Long Lake
Long Lake in Hubbard County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.2 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 4.5 µg/L. Maximum depth: 135 ft. Surface area: 1926.11 acres.
- Clarity
- 11.2 ft
- Typical in August
- 58°F
- Max depth
- 135 ft
- Area
- 1,926 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 23
- Open water
- 237 days
Next lake in Hubbard County
Free interactive depth-contour map of Long Lake, reaching a maximum surveyed depth of 120 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Long Lake is a 1,926-acre mesotrophic lake in Hubbard County, Minnesota with a maximum depth of 135 feet (31-foot average). Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 14 documented fish species including black crappie, bluegill, and bowfin (dogfish). Public access is available with 1 public boat landing. Compared to the 67 other monitored lakes in Hubbard County, Long Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-22. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 11.2 ft. Phosphorus level: 10 µg/L. Chlorophyll-a: 4.5 µg/L. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11.2 ft | Not graded |
| Phosphorus | 10 µg/L | Good |
| Chlorophyll-a (Algae) | 4.5 µg/L | Good |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long 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.
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Water Temperature
Long Lake typically sits around 58°F at the surface in August. Summer average is about 56°F. Usually warmest in Jul (about 58°F) and coldest in May (about 53°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 250 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 (135,519 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 | 135 ft |
| Average Depth | 31 ft |
| Surface Area | 1,926 acres |
| Shoreline Length | 18.9 mi |
| Littoral Zone | 24% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Spruce Hill CampgroundSemi-private
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
12 surveys on file from MN DNR Fisheries. Most recent: 2024-06-28 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluntnose Minnow | 39.39 | — |
| Bluegill | 22.99 | 0.09 lb |
| IOD | 22.85 | — |
| Tullibee (Cisco) | 15.03 | 0.64 lb |
| MMS | 7.72 | — |
| JND | 5.55 | — |
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
Tullibee (Cisco)
From the 2024-06-28 survey
Long Lake is located two miles east of Park Rapids in Hubbard County. Long Lake has a surface area of 1,926 acres and a maximum depth of 135 feet. A DNR-owned access is located on the north end of the lake off County Road 107 and a County owned access is located on the south end of the lake off Delaney Lane. Long Lake…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Long Lake. 4 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
- —Aquatic Plant Report — Long (1270)Aquatic Plant Report · 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: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.068 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.41 µg/L/yr | 6 |
| Chlorophyll-a | → Stable | -0.02 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (68 observations).
Estimated open water season: 237 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2012-03-27 (2012) | 1996-05-10 (1996) |
| Ice-In | 1995-11-24 (1995) | 2024-01-12 (2024) |
Most recent ice-out: 2025-04-19
Reservoir Info (USACE NID)
Long Lake is a man-made reservoir impounded by the Long Lake (completed 1949), built primarily for recreation on the Shell River; earth-type dam, 25 ft tall and 150 ft long.
- Surface area
- 1,863 ac
- Normal storage
- 57,753 ac-ft
- Max storage
- 57,753 ac-ft
- Drainage area
- 35 sq mi
- Hazard class
- Low
- Owner
- MNDNR
Source: USACE National Inventory of Dams, NID ID MN00187 · Operator website
EPA Impairment Status
Long Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN29-0161-00 · Official waterbody report
County Ranking
Ranked #1 of 68 lakes in Hubbard County
Nearby Lakes in Hubbard County
Frequently asked questions about Long Lake
What is the water quality grade for Long Lake?
- Long Lake in Hubbard County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.2 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 4.5 µg/L. Maximum depth: 135 ft. Surface area: 1926.11 acres.
Is Long Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Long Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 4.5 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Long Lake?
- Long Lake typically sits around 58°F at the surface in August, from 250 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 135 feet and an average depth of 31 feet. The lake covers 1926.11 acres.
What fish are in Long Lake?
- Fish species found in Long Lake include black crappie, bluegill, bowfin (dogfish), brown bullhead, largemouth bass, northern pike, pumpkinseed, rock bass, smallmouth bass, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Long Lake is located in Hubbard County, Minnesota.
When does Long Lake thaw?
- Long Lake typically has ice-out around Apr 23. Ice typically forms around Dec 16. The open water season is approximately 237 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 (135,519 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 Spruce Hill Campground. Public access is listed as yes.
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Hubbard County · Grade A
Hubbard County · Grade A
Hubbard County · Grade A
Hubbard County · Grade A
Hubbard County · Grade A
Hubbard County · Grade A
Where this data comes from
105 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
MNPCA105 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