Long Lake
Long Lake in Stearns County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2.5 ft visibility. Phosphorus: 61 µg/L. Chlorophyll-a (algae): 41 µg/L. Maximum depth: 35 ft. Surface area: 487.12 acres.
- Clarity
- 2.5 ft
- Typical in August
- 60°F
- Max depth
- 35 ft
- Area
- 487 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
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 Stearns County
Long Lake is a 487-acre productive, nutrient-rich eutrophic lake in Stearns County, Minnesota with a maximum depth of 35 feet (10-foot average). Water quality is graded F based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 23 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 31 other monitored lakes in Stearns County, Long Lake ranks #24 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-25. Grade methodology: LakeGrade methodology.
Watch Long Lake water quality
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Swimming Safety
Grade onlyLimited data
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 2.5 ft of visibility. Phosphorus level: 61 µg/L. Chlorophyll-a: 41 µg/L. Trophic State Index: 65.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.5 ft | Not graded |
| Phosphorus | 61 µg/L | Poor |
| Chlorophyll-a (Algae) | 41 µg/L | Poor |
| Trophic State Index (TSI) | 65 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long Lake in Stearns 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 60°F at the surface in August. Summer average is about 59°F. Usually warmest in Jul (about 61°F) and coldest in May (about 51°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 239 field readings (2018–2025) 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 very high (1,770,109 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 | 35 ft |
| Average Depth | 10 ft |
| Surface Area | 487 acres |
| Shoreline Length | 9.2 mi |
| Littoral Zone | 62% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- RichmondPublic
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
18 surveys on file from MN DNR Fisheries. Most recent: 2025-10-09 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 18.96 | 0.24 lb |
| Yellow Perch | 18.31 | 0.14 lb |
| Bluntnose Minnow | 18.02 | — |
| Walleye | 15.95 | 2.07 lb |
| Black Crappie | 13.74 | 0.26 lb |
| Largemouth Bass | 12.42 | 1.17 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
Yellow Perch
Walleye
Black Crappie
From the 2025-10-09 survey
Long Lake is a 487-acre lake located four miles north of Eden Valley in south central Stearns County. The lake is moderately productive, has a maximum depth of 35 feet, and is conjoined to the Sauk River Chain of Lakes through a navigable channel from Horseshoe Lake. The lake is managed primarily for Walleye; however,…
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 | ↓ Declining | -0.108 m/yr | 6 |
| Phosphorus | ↓ Declining | +11.69 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +6.44 µg/L/yr | 6 |
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 MN73-0139-00 · Official waterbody report
County Ranking
Ranked #24 of 32 lakes in Stearns 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.
Nearby Lakes in Stearns County
Frequently asked questions about Long Lake
What is the water quality grade for Long Lake?
- Long Lake in Stearns County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2.5 ft visibility. Phosphorus: 61 µg/L. Chlorophyll-a (algae): 41 µg/L. Maximum depth: 35 ft. Surface area: 487.12 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 41 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Long Lake?
- Long Lake typically sits around 60°F at the surface in August, from 239 EPA Water Quality Portal field readings (2018–2025). That is a typical value for the month, not a live reading.
How deep is Long Lake?
- Long Lake has a maximum depth of 35 feet and an average depth of 10 feet. The lake covers 487.12 acres.
What fish are in Long Lake?
- Fish species found in Long Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, channel catfish, common carp, greater redhorse, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, redhorse, rock bass, shorthead redhorse, silver redhorse, smallmouth bass, smallmouth buffalo, walleye, white sucker, yellow bullhead, yellow perch. Long Lake is located in Stearns County, Minnesota.
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 very high (1,770,109 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 Richmond. Public access is listed as yes.
Explore Long Lake across LakeGrade
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Species activity outlook by water temperature and season
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High nutrients, frequent algae, reduced clarity
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Where this data comes from
83 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
MNPCA83 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
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