Stony Lake
Cass County, Minnesota563 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Stony Lake. Here is what has been measured.
- Oligotrophic
- Impaired · Mercury
- 50 ft max depth
- Public access
Stony Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 23 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 2 µg/L. Maximum depth: 50 ft. Surface area: 563.21 acres.
Minnesota DNR's Standard Survey on June 5, 2023 caught 1.67 walleye per gill net at Stony Lake. DNR survey details →
Stony Lake is a 563-acre cold, clear oligotrophic lake in Cass County, Minnesota with a maximum depth of 50 feet. Overall water quality is improving over recent sampling years. The lake supports 12 documented fish species including black crappie, bluegill, and hybrid sunfish. Public access is available with 1 public boat landing. Compared to the 103 other monitored lakes in Cass County, Stony Lake ranks #52 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-29. Methodology: how these readings are compared.
Stony Lake covers about 560 acres in Cass County. It has one public boat landing. The median ice-out date is April 22, which is when the open-water season begins. For a place on the water, look through cabin and lake-house rentals near Stony Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Stony Lake is good for
From access and monitoring records, not editorial picks.
- Clear water23 ft of visibility
- Boat launch1 documented ramp
- Fishing12 species recorded
- Ice seasonIce-out around Apr 22
- Deep water50 ft surveyed max depth
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Stony Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Stony Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Stony Lake
These are the measurements Minnesota PCA publishes for Stony Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 23 ft down. Phosphorus 7 µg/L. Chlorophyll-a 2 µg/L. TSI 34.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 23ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 7µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 2µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 34 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Stony Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Stony Lake typically sits around 68°F at the surface in September. Summer average is about 72°F. Usually warmest in Jul (about 76°F) and coldest in Jun (about 68°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (68°F) to its warmest (76°F).
Typical surface water temperature by month, from 37 field readings (2010–2024) via the EPA Water Quality Portal. See the full Stony Lake water temperature breakdown →
Minnesota DNR's Standard Survey on June 5, 2023 caught 1.67 walleye per gill net at Stony Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Stony Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
12 surveys on file from MN DNR Fisheries. Most recent: 2023-06-05 (Standard Survey).
12 surveys on file · most recent 2023-06-05 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluegill | 27.26 | 3–9 in 2023-06-05 | 0.11 lb |
| Yellow Perch | 9.59 | 5–7 in 2023-06-05 | 0.21 lb |
| Rock Bass | 8.07 | 3–11 in 2023-06-05 | 0.41 lb |
| Largemouth Bass | 7.79 | 5–15 in 2023-06-05 | 0.94 lb |
| Northern Pike | 6.55 | 9–38 in 2023-06-05 | 1.54 lb |
| Smallmouth Bass | 6.36 | 11–13 in 2023-06-05 | 1.53 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and 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
Yellow Perch
Rock Bass
Largemouth Bass
From the 2023-06-05 survey
Stony Lake is a 563-acre lake with 6.58 miles of shoreline and a maximum depth of 50 feet located east of Hackensack, MN. A Minnesota Department of Natural Resources (MNDNR) owned public access is located on the south shore. The DNR has classified Minnesota's lakes into 43 different classes based on physical,…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Stony Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — StonyFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Stony (1481)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — StonyFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — StonyPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
50 ft
Surface area
563 acres
Shoreline
6.6 mi
Littoral zone
32%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
5 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,371 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Stony LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Stony Lake
Compare lakeside cabins, hotels, and vacation rentals near Stony Lake in Cass 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 Stony Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
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Fish Species
Click a species to see every lake where it is documented.
Fishing Stony Lake
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Phosphorus
Improving-0.17 µg/L/yr6 years
Chlorophyll-a
Improving-0.17 µg/L/yr6 years
Ice season
Typical ice-out
Apr 22
Earliest Apr 3, 2024 · Latest May 9, 2008
Typical ice-in
Nov 28
Earliest Nov 7, 1991 · Latest Dec 20, 2001
Most recent ice-out
Apr 3
2024
79 observations · Minnesota PCA ice records
EPA Impairment Status
Stony Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN11-0371-00 · Official waterbody report
Nearby Lakes in Cass County
Frequently asked questions about Stony Lake
Where is Stony Lake?
- Stony Lake is a lake in Cass County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Stony Lake?
- Stony Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 23 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 2 µg/L. Maximum depth: 50 ft. Surface area: 563.21 acres.
Is Stony Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Stony Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
What is the water temperature of Stony Lake?
- Stony Lake typically sits around 68°F at the surface in September, from 37 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
How deep is Stony Lake?
- Stony Lake has a maximum depth of 50 feet. The lake covers 563.21 acres.
What fish are in Stony Lake?
- Fish species found in Stony Lake include black crappie, bluegill, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, smallmouth bass, walleye, white sucker, yellow bullhead, yellow perch. Stony Lake is located in Cass County, Minnesota.
What did the DNR fisheries survey find at Stony Lake?
- Minnesota DNR's Standard Survey on June 5, 2023 caught 1.67 walleye per gill net at Stony Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Stony Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
When does Stony Lake thaw?
- Stony Lake typically has ice-out around Apr 22. Ice typically forms around Nov 28. The open water season is approximately 220 days.
Are there boat ramps on Stony Lake?
- Stony Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Stony Lake. Public access is listed as yes.
Can I fish at Stony Lake?
- Stony Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Stony Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in Cass County
Species activity outlook by water temperature and season
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Where to stay at Minnesota's top lakes, each with its readings
Lakes in the Mississippi Headwaters, ranked by water quality
Lakes in the Pine River Watersheds (Brainerd Lakes), ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
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Compare Stony Lake With Nearby Lakes
Where this data comes from
92 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
MNPCA92 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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from 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