Big Mcdonald Lake
Big Mcdonald Lake in Otter Tail County, Minnesota has a water quality grade of A (Excellent). Water clarity: 17.4 ft visibility. Phosphorus: 12 µg/L. Chlorophyll-a (algae): 3.2 µg/L. Maximum depth: 46 ft. Surface area: 991.7 acres.
- Clarity
- 17.4 ft
- Typical in August
- 72°F
- Max depth
- 46 ft
- Area
- 992 acres
- Type
- Oligotrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 17
- Open water
- 224 days
Next lake in Otter Tail County
Big Mcdonald Lake is a 992-acre cold, clear oligotrophic lake in Otter Tail County, Minnesota with a maximum depth of 46 feet. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 15 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 2 public boat landings. Compared to the 65 other monitored lakes in Otter Tail County, Big Mcdonald Lake ranks #13 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)
Crystal clear, you can see 17.4 ft down. Phosphorus level: 12 µg/L. Chlorophyll-a: 3.2 µg/L. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 17.4 ft | Not graded |
| Phosphorus | 12 µg/L | Good |
| Chlorophyll-a (Algae) | 3.2 µg/L | Good |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Big Mcdonald Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Mcdonald 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.
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Water Temperature
Big Mcdonald Lake typically sits around 72°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 75°F) and coldest in May (about 54°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 34 field readings (2010–2025) via the EPA Water Quality Portal. See the full Big Mcdonald Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Big Mcdonald Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (22,491 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 | 46 ft |
| Surface Area | 992 acres |
| Shoreline Length | 5.8 mi |
| Littoral Zone | 37% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Big McDonald LakePublic
- McDonald Lake, Seclusion PointPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Big Mcdonald 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
9 surveys on file from MN DNR Fisheries. Most recent: 2025-08-19 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| MMS | 131.49 | — |
| Largemouth Bass | 26.18 | 0.68 lb |
| Yellow Bass | 21.11 | 0.72 lb |
| Bluegill | 19.53 | 0.23 lb |
| Bluntnose Minnow | 12.14 | — |
| Green Sunfish | 6.31 | — |
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.
Largemouth Bass
Yellow Bass
Bluegill
From the 2025-08-19 survey
Big McDonald Lake is a 935-acre mesotrophic (moderately fertile) lake located in north-central Otter Tail County approximately nine miles west of Perham, MN. Big McDonald Lake is located within 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 Big Mcdonald Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Big McDonaldFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — Big McDonaldFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Big McDonaldPublic 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 | +0.3 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.24 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.11 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (24 observations).
Estimated open water season: 224 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2021-04-02 (2021) | 2022-05-06 (2022) |
| Ice-In | 2007-11-07 (2007) | 2015-12-19 (2015) |
Most recent ice-out: 2024-04-05
EPA Impairment Status
Big Mcdonald 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 MN56-0386-01 · Official waterbody report
County Ranking
Ranked #13 of 66 lakes in Otter Tail County
Nearby Lakes in Otter Tail County
Frequently asked questions about Big Mcdonald Lake
What is the water quality grade for Big Mcdonald Lake?
- Big Mcdonald Lake in Otter Tail County, Minnesota has a water quality grade of A (Excellent). Water clarity: 17.4 ft visibility. Phosphorus: 12 µg/L. Chlorophyll-a (algae): 3.2 µg/L. Maximum depth: 46 ft. Surface area: 991.7 acres.
Is Big Mcdonald Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Big Mcdonald Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 3.2 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Big Mcdonald Lake?
- Big Mcdonald Lake typically sits around 72°F at the surface in August, from 34 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Big Mcdonald Lake?
- Big Mcdonald Lake has a maximum depth of 46 feet. The lake covers 991.7 acres.
What fish are in Big Mcdonald Lake?
- Fish species found in Big Mcdonald Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, walleye, yellow bullhead, yellow perch. Big Mcdonald Lake is located in Otter Tail County, Minnesota.
When does Big Mcdonald Lake thaw?
- Big Mcdonald Lake typically has ice-out around Apr 17. Ice typically forms around Nov 27. The open water season is approximately 224 days.
Does Big Mcdonald Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Big Mcdonald Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (22,491 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Big Mcdonald Lake?
- Big Mcdonald Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Big McDonald Lake, McDonald Lake, Seclusion Point. Public access is listed as yes.
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Where this data comes from
263 measurements from 4 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
MNPCA263 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Phosphorus by Colorimetry
- 2120 B ~ Color in Water by Visual Comparison
Monitoring station identifiers (4)
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