Marion Lake
Marion Lake in Otter Tail County, Minnesota has a water quality grade of B (Good). Water clarity: 11 ft visibility. Phosphorus: 18 µg/L. Chlorophyll-a (algae): 7.3 µg/L. Maximum depth: 62 ft. Surface area: 1623.77 acres.
- Clarity
- 11 ft
- Typical in August
- 75°F
- Max depth
- 62 ft
- Area
- 1,624 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 16
- Open water
- 226 days
Next lake in Otter Tail County
Free interactive depth-contour map of Marion Lake, reaching a maximum surveyed depth of 60 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Marion Lake is a 1,624-acre mesotrophic lake in Otter Tail County, Minnesota with a maximum depth of 62 feet. Water quality is graded B based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 17 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 65 other monitored lakes in Otter Tail County, Marion Lake ranks #51 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-02. 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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Good clarity, visible to about 11 ft. Phosphorus level: 18 µg/L. Chlorophyll-a: 7.3 µg/L. Trophic State Index: 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11 ft | Not graded |
| Phosphorus | 18 µg/L | Good |
| Chlorophyll-a (Algae) | 7.3 µg/L | Good |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Marion Lake
Compare lakeside cabins, hotels, and vacation rentals near Marion Lake in Otter Tail 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.
Top-rated places to stay near Marion Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Marion Lake typically sits around 75°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 76°F) and coldest in May (about 56°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 101 field readings (2010–2025) via the EPA Water Quality Portal. See the full Marion Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Marion Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (111,686 cells/mL) on November 2, 2024.
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 | 62 ft |
| Surface Area | 1,624 acres |
| Shoreline Length | 9.1 mi |
| Littoral Zone | 42% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Marion LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Marion 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: 2025-06-23 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluntnose Minnow | 133.78 | — |
| BKF | 58.34 | — |
| Bluegill | 47.08 | 0.16 lb |
| Yellow Perch | 20.18 | 0.15 lb |
| Yellow Bass | 15.86 | 0.74 lb |
| Hybrid Sunfish | 9.19 | 0.26 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
Yellow Bass
Hybrid Sunfish
From the 2025-06-23 survey
Marion Lake is a 1,664-acre mesotrophic (moderately fertile) lake located in north-central Otter Tail County approximately four miles southwest of Perham, MN. Marion Lake is included in the Otter Tail River Watershed. The immediate watershed is primarily composed of agricultural land interspersed with hardwood…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Marion Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — MarionFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — MarionFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — MarionPublic 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 | ↑ Improving | +0.2 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.9 µg/L/yr | 6 |
| Chlorophyll-a | → Stable | -0.01 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (48 observations).
Estimated open water season: 226 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-16 (2024) | 2022-05-07 (2022) |
| Ice-In | 1997-11-10 (1997) | 2015-12-19 (2015) |
Most recent ice-out: 2024-03-16
EPA Impairment Status
Marion 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 MN56-0243-00 · Official waterbody report
County Ranking
Ranked #51 of 66 lakes in Otter Tail County
Nearby Lakes With Higher Grades
Marion Lake holds Grade B. 3 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 Otter Tail County
Frequently asked questions about Marion Lake
What is the water quality grade for Marion Lake?
- Marion Lake in Otter Tail County, Minnesota has a water quality grade of B (Good). Water clarity: 11 ft visibility. Phosphorus: 18 µg/L. Chlorophyll-a (algae): 7.3 µg/L. Maximum depth: 62 ft. Surface area: 1623.77 acres.
Is Marion Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Marion Lake has a water quality grade of B (Good). Algae concentration (chlorophyll-a) is 7.3 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Marion Lake?
- Marion Lake typically sits around 75°F at the surface in August, from 101 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Marion Lake?
- Marion Lake has a maximum depth of 62 feet. The lake covers 1623.77 acres.
What fish are in Marion Lake?
- Fish species found in Marion Lake include black bullhead, 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. Marion Lake is located in Otter Tail County, Minnesota.
When does Marion Lake thaw?
- Marion Lake typically has ice-out around Apr 16. Ice typically forms around Nov 28. The open water season is approximately 226 days.
Does Marion Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Marion Lake (clouds, ice, or an off-season gap). The most recent reading was high (111,686 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Marion Lake?
- Marion Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Marion Lake. Public access is listed as yes.
Explore Marion Lake across LakeGrade
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Where this data comes from
382 measurements from 3 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA382 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 (3)
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