Crystal Lake
Cass County, Minnesota190 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Crystal Lake. Here is what has been measured.
- Oligotrophic
- Impaired · Mercury
- 40 ft max depth
- Public access
- Limited data
Crystal Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 16 ft visibility. Phosphorus: 7.5 µg/L. Chlorophyll-a (algae): 2.3 µg/L. Maximum depth: 40 ft. Surface area: 190.2 acres.
Minnesota DNR's Standard Survey on July 15, 2025 caught 1.00 walleye per gill net at Crystal Lake. DNR survey details →
Crystal Lake is a 190-acre cold, clear oligotrophic lake in Cass County, Minnesota with a maximum depth of 40 feet. The lake supports 10 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, Crystal Lake ranks #28 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-08-30. Methodology: how these readings are compared.
What Crystal Lake is good for
From access and monitoring records, not editorial picks.
- Clear water16 ft of visibility
- Boat launch1 documented ramp
- Fishing10 species recorded
- Ice seasonIce-out around Apr 16
- Deep water40 ft surveyed max depth
Swimming conditions
Readings onlyLimited data
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. Crystal Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Crystal 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 Crystal Lake
These are the measurements Minnesota PCA publishes for Crystal 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 16 ft down. Phosphorus 7.5 µg/L. Chlorophyll-a 2.3 µg/L. TSI 36.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 16ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 7.5µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 2.3µg/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. | 36 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Crystal Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Crystal Lake typically sits around 53°F at the surface in October. Summer average is about 71°F. Usually warmest in Jul (about 74°F) and coldest in Oct (about 53°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (53°F) to its warmest (74°F).
Typical surface water temperature by month, from 72 field readings (2011–2025) via the EPA Water Quality Portal. See the full Crystal Lake water temperature breakdown →
Minnesota DNR's Standard Survey on July 15, 2025 caught 1.00 walleye per gill net at Crystal Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Crystal Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
11 surveys on file from MN DNR Fisheries. Most recent: 2025-07-15 (Standard Survey).
11 surveys on file · most recent 2025-07-15 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluntnose Minnow | 139.42 | ||
| Largemouth Bass | 23.79 | 4–16 in 2025-07-15 | 0.64 lb |
| Bluegill | 19.31 | 3–9 in 2025-07-15 | 0.19 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.
Largemouth Bass
Bluegill
From the 2025-07-15 survey
Crystal Lake (DOW #11-0502-00) is located five miles southeast of Akeley on the border of Hubbard and Cass Counties. Crystal Lake has a surface area of 190 acres and a maximum depth of 40 feet. There is a state-owned public access located on the southeast shore of the lake off Hiram Twp 5 Road. Crystal Lake has…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Crystal Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — CrystalFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Crystal (1309)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — CrystalFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — CrystalPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
40 ft
Surface area
190 acres
Shoreline
3.5 mi
Littoral zone
86%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
2 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,394 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Crystal 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 Crystal Lake
Compare lakeside cabins, hotels, and vacation rentals near Crystal 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 Crystal Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Crystal Lake
Water Quality Trend: Stable
Based on 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Ice season
Typical ice-out
Apr 16
Earliest Apr 10, 2007 · Latest Apr 30, 2008
Typical ice-in
Nov 13
Earliest Nov 2, 2006 · Latest Nov 28, 2001
Most recent ice-out
Apr 30
2008
15 observations · Minnesota PCA ice records
EPA Impairment Status
Crystal 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 MN11-0502-00 · Official waterbody report
Nearby Lakes in Cass County
Frequently asked questions about Crystal Lake
Where is Crystal Lake?
- Crystal 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 Crystal Lake?
- Crystal Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 16 ft visibility. Phosphorus: 7.5 µg/L. Chlorophyll-a (algae): 2.3 µg/L. Maximum depth: 40 ft. Surface area: 190.2 acres.
Is Crystal Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Crystal 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 Crystal Lake?
- Crystal Lake typically sits around 53°F at the surface in October, from 72 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Crystal Lake?
- Crystal Lake has a maximum depth of 40 feet. The lake covers 190.2 acres.
What fish are in Crystal Lake?
- Fish species found in Crystal Lake include black crappie, bluegill, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white sucker, yellow bullhead, yellow perch. Crystal Lake is located in Cass County, Minnesota.
What did the DNR fisheries survey find at Crystal Lake?
- Minnesota DNR's Standard Survey on July 15, 2025 caught 1.00 walleye per gill net at Crystal Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Crystal Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
When does Crystal Lake thaw?
- Crystal Lake typically has ice-out around Apr 16. Ice typically forms around Nov 13. The open water season is approximately 211 days.
Are there boat ramps on Crystal Lake?
- Crystal Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Crystal Lake. Public access is listed as yes.
Can I fish at Crystal Lake?
- Crystal 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 Crystal Lake across LakeQuality
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Where this data comes from
104 measurements from 2 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
MNPCA104 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 (2)
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