Mary Lake
Mary Lake in Wright County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5 ft visibility. Maximum depth: 102 ft. Surface area: 196.03 acres.
- Clarity
- 5 ft
- Typical in August
- 64°F
- Max depth
- 102 ft
- Area
- 196 acres
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 4
Next lake in Wright County
Why Mary 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 Mary Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not 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.
Mary Lake is a 196-acre lake in Wright County, Minnesota with a maximum depth of 102 feet (35-foot average). Overall water quality is declining over recent sampling years. The lake supports 13 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 2025-09-27. 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 Mary Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 5 ft. Trophic State Index: 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Mary Lake
Compare lakeside cabins, hotels, and vacation rentals near Mary Lake in Wright 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 Mary Lake
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Water Temperature
Mary Lake typically sits around 64°F at the surface in August. Summer average is about 61°F. Usually warmest in Aug (about 64°F) and coldest in Oct (about 57°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 134 field readings (2022–2025) via the EPA Water Quality Portal.
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 102 ft |
| Average Depth | 35.1 ft |
| Surface Area | 196 acres |
| Shoreline Length | 2.4 mi |
| Littoral Zone | 42% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Mary LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Mary 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
6 surveys on file from MN DNR Fisheries. Most recent: 2017-08-14 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 26.55 | 0.14 lb |
| Largemouth Bass | 12.03 | 1.07 lb |
| Yellow Perch | 11.10 | 0.09 lb |
| Green Sunfish | 10.18 | 0.04 lb |
| Black Bullhead | 8.27 | 0.55 lb |
| Black Crappie | 5.19 | 0.22 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
Largemouth Bass
Yellow Perch
Green Sunfish
From the 2017-08-14 survey
Mary Lake is a 209 acre general development lake located two miles north of Maple Lake in central Wright County. A public access is located on the northwest side of the lake with room for 4 - 6 truck/trailer rigs. Mary Lake has a maximum depth of 102 feet and water clarity is fair with an average summer Secchi reading…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Mary Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — MaryFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Mary (2016)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — MaryFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — MaryPublic 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 | -0.28 m/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (7 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2017-03-08 (2017) | 2008-04-23 (2008) |
| Ice-In | 2007-12-03 (2007) | 2004-12-14 (2004) |
Most recent ice-out: 2017-03-08
EPA Impairment Status
Mary 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 MN86-0156-00 · Official waterbody report
Graded lakes near Mary Lake
Mary Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Wright County
Frequently asked questions about Mary Lake
What is the water quality grade for Mary Lake?
- Mary Lake in Wright County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5 ft visibility. Maximum depth: 102 ft. Surface area: 196.03 acres.
Is Mary Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Mary Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What is the water temperature of Mary Lake?
- Mary Lake typically sits around 64°F at the surface in August, from 134 EPA Water Quality Portal field readings (2022–2025). That is a typical value for the month, not a live reading.
How deep is Mary Lake?
- Mary Lake has a maximum depth of 102 feet and an average depth of 35.1 feet. The lake covers 196.03 acres.
What fish are in Mary Lake?
- Fish species found in Mary Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, yellow bullhead, yellow perch. Mary Lake is located in Wright County, Minnesota.
When does Mary Lake thaw?
- Mary Lake typically has ice-out around Apr 4.
Are there boat ramps on Mary Lake?
- Mary Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Mary Lake. Public access is listed as yes.
Explore Mary Lake across LakeGrade
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Where this data comes from
50 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
MNPCA50 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
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