Long Lake
Long Lake in Todd County, Minnesota has a water quality grade of C (Fair). Water clarity: 10.1 ft visibility. Phosphorus: 25 µg/L. Chlorophyll-a (algae): 7 µg/L. Maximum depth: 63 ft. Surface area: 398.67 acres.
Minnesota DNR surveys at Long Lake average 17.71 largemouth bass per unit of sampling effort (CPUE) across 13 surveys. The most recent is a Targeted Survey dated August 15, 2024. Length samples in the latest survey that recorded them ran 7–18 inches. DNR survey details →
- Clarity
- 10.1 ft
- Typical in August
- 64°F
- Max depth
- 63 ft
- Area
- 399 acres
- Type
- Mesotrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 17
- Open water
- 236 days
Next lake in Todd County
Long Lake is a 399-acre mesotrophic lake in Todd County, Minnesota with a maximum depth of 63 feet (40-foot average). Water quality is graded C based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 16 documented fish species including black crappie, bluegill, and bowfin (dogfish). Public access is available with 2 public boat landings. Compared to the 7 other monitored lakes in Todd County, Long Lake ranks #3 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 onlyModerate
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Good clarity, visible to about 10.1 ft. Phosphorus level: 25 µg/L. Chlorophyll-a: 7 µg/L. Trophic State Index: 48.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.1 ft | Not graded |
| Phosphorus | 25 µg/L | Fair |
| Chlorophyll-a (Algae) | 7 µg/L | Good |
| Trophic State Index (TSI) | 48 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long Lake in Todd 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 64°F at the surface in August. Summer average is about 63°F. Usually warmest in Jul (about 70°F) and coldest in Jun (about 56°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 158 field readings (2016–2025) 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 (277,971 cells/mL) on May 30, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Minnesota DNR surveys at Long Lake average 17.71 largemouth bass per unit of sampling effort (CPUE) across 13 surveys. The most recent is a Targeted Survey dated August 15, 2024. Length samples in the latest survey that recorded them ran 7–18 inches.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Long Lake C from EPA Water Quality Portal chemistry, and the water-quality trend over 5 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
13 surveys on file from MN DNR Fisheries. Most recent: 2024-08-15 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg catch rate (CPUE) | Avg Weight |
|---|---|---|
| Bluegill | 26.75 | 0.15 lb |
| Largemouth Bass | 17.71 | 1.05 lb |
| Yellow Bass | 9.14 | 0.83 lb |
| Yellow Perch | 7.09 | 0.13 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE means more abundant in standardized sampling. This is not a weekly bite report.
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
Largemouth Bass
Yellow Bass
Yellow Perch
From the 2024-08-15 survey
Temperature and dissolved oxygen measurements were collected from the deepest basin in Long Lake on August 15th, 2024, to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Cisco, also known as Tullibee, the most sensitive coldwater species present in this lake. During…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Long Lake. 5 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 (1059)Aquatic Plant Report · MN DNR LakeFinder
- —Aquatic Plant Report — Long (2031)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
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 63 ft |
| Average Depth | 40 ft |
| Surface Area | 399 acres |
| Shoreline Length | 4 mi |
| Littoral Zone | 20% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Bass LakePublic
- Long LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Long Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.138 m/yr | 5 |
| Phosphorus | ↓ Declining | +1.08 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +0.2 µg/L/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (33 observations).
Estimated open water season: 236 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2012-03-20 (2012) | 2013-05-11 (2013) |
| Ice-In | 2014-11-24 (2014) | 2024-01-10 (2024) |
Most recent ice-out: 2023-04-30
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
Source: EPA ATTAINS assessment unit MN77-0027-00 · Official waterbody report
County Ranking
Ranked #3 of 8 lakes in Todd County
Nearby Lakes With Higher Grades
Long Lake holds Grade C. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Todd County
Frequently asked questions about Long Lake
What is the water quality grade for Long Lake?
- Long Lake in Todd County, Minnesota has a water quality grade of C (Fair). Water clarity: 10.1 ft visibility. Phosphorus: 25 µg/L. Chlorophyll-a (algae): 7 µg/L. Maximum depth: 63 ft. Surface area: 398.67 acres.
Is Long Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Long Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 7 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Long Lake?
- Long Lake typically sits around 64°F at the surface in August, from 158 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.
How deep is Long Lake?
- Long Lake has a maximum depth of 63 feet and an average depth of 40 feet. The lake covers 398.67 acres.
What fish are in Long Lake?
- Fish species found in Long Lake include black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Long Lake is located in Todd County, Minnesota.
What did the DNR fisheries survey find at Long Lake?
- Minnesota DNR surveys at Long Lake average 17.71 largemouth bass per unit of sampling effort (CPUE) across 13 surveys. The most recent is a Targeted Survey dated August 15, 2024. Length samples in the latest survey that recorded them ran 7–18 inches. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Long Lake C from EPA Water Quality Portal chemistry, and the water-quality trend over 5 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
When does Long Lake thaw?
- Long Lake typically has ice-out around Apr 17. Ice typically forms around Dec 9. The open water season is approximately 236 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 (277,971 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 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Bass Lake, Long Lake. Public access is listed as yes.
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Where this data comes from
94 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
MNPCA94 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