Mason Lake
Mason Lake in Otter Tail County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3 ft visibility. Phosphorus: 21 µg/L. Chlorophyll-a (algae): 16.9 µg/L. Maximum depth: 108 ft. Surface area: 5614.95 acres.
- Clarity
- 3 ft
- Max depth
- 108 ft
- Area
- 5,615 acres
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 15
- Open water
- 229 days
Next lake in Otter Tail County
Why Mason Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Mason Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Mason Lake is a 5,615-acre lake in Otter Tail County, Minnesota with a maximum depth of 108 feet. 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.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-08-02. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Mason Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 3 ft of visibility. Phosphorus level: 21 µg/L. Chlorophyll-a: 16.9 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 21 µg/L | Not graded |
| Chlorophyll-a (Algae) | 16.9 µg/L | Not graded |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Mason Lake
Compare lakeside cabins, hotels, and vacation rentals near Mason 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 Mason Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 108 ft |
| Surface Area | 5,615 acres |
| Shoreline Length | 17.1 mi |
| Littoral Zone | 44% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- West Battle Lake (East)Public
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Mason 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
11 surveys on file from MN DNR Fisheries. Most recent: 2025-04-21 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 33.78 | 0.14 lb |
| Yellow Perch | 11.42 | 0.17 lb |
| Rock Bass | 5.70 | 0.39 lb |
| Pumpkinseed | 5.57 | 0.21 lb |
| Hybrid Sunfish | 5.11 | 0.23 lb |
| Northern Pike | 3.56 | 2.16 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
Rock Bass
Pumpkinseed
From the 2025-04-21 survey
West Battle Lake is a 5,624-acre mesotrophic (moderately fertile) lake located in south-central Otter Tail County. The city of Battle Lake, Minnesota abuts the west shoreline. The immediate watershed is composed primarily of agricultural land interspersed with hardwood woodlots. The maximum depth is 108 feet; however,…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Mason Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — West BattleFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — West Battle (1195)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — West BattleFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — West BattlePublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.685 m/yr | 3 |
Ice Season
Historical ice data from Minnesota DNR (57 observations).
Estimated open water season: 229 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-19 (2024) | 2013-05-13 (2013) |
| Ice-In | 2002-11-26 (2002) | 2001-12-20 (2001) |
Most recent ice-out: 2025-04-11
Graded lakes near Mason Lake
Mason Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Otter Tail County
Frequently asked questions about Mason Lake
What is the water quality grade for Mason Lake?
- Mason Lake in Otter Tail County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3 ft visibility. Phosphorus: 21 µg/L. Chlorophyll-a (algae): 16.9 µg/L. Maximum depth: 108 ft. Surface area: 5614.95 acres.
Is Mason Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Mason Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Algae concentration (chlorophyll-a) is 16.9 µg/L. Always check local health department advisories before swimming.
How deep is Mason Lake?
- Mason Lake has a maximum depth of 108 feet. The lake covers 5614.95 acres.
What fish are in Mason Lake?
- Fish species found in Mason Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, muskellunge, northern pike, pumpkinseed, rock bass, walleye, white sucker, yellow bullhead, yellow perch. Mason Lake is located in Otter Tail County, Minnesota.
When does Mason Lake thaw?
- Mason Lake typically has ice-out around Apr 15. Ice typically forms around Nov 30. The open water season is approximately 229 days.
Are there boat ramps on Mason Lake?
- Mason Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include West Battle Lake (East). Public access is listed as yes.
Explore Mason Lake across LakeGrade
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Where this data comes from
4 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA4 samples · 2023
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2120 B ~ Color in Water by Visual Comparison
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
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