Crystal Lake
Crystal Lake in Cass County, Minnesota has a water quality grade of A (Excellent). 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.
- Clarity
- 16 ft
- Typical in August
- 70°F
- Max depth
- 40 ft
- Area
- 190 acres
- Type
- Oligotrophic
- Trend
- → Stable
- Public access
- Yes
- Ice-out
- Apr 16
- Open water
- 211 days
Next lake in Cass County
Crystal Lake is a 190-acre cold, clear oligotrophic lake in Cass County, Minnesota with a maximum depth of 40 feet. Water quality is graded A based on 2 sampling years through 2025. The lake supports 10 documented fish species including black crappie, bluegill, and hybrid sunfish. Public access is available with 2 public boat landings. 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. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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 16 ft down. Phosphorus level: 7.5 µg/L. Chlorophyll-a: 2.3 µg/L. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16 ft | Not graded |
| Phosphorus | 7.5 µg/L | Good |
| Chlorophyll-a (Algae) | 2.3 µg/L | Good |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay 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.
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Water Temperature
Crystal Lake typically sits around 70°F at the surface in August. 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.
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 →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 40 ft |
| Surface Area | 190 acres |
| Shoreline Length | 3.5 mi |
| Littoral Zone | 86% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Crystal LakePublic
- Ten Mile LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Crystal Lake
DNR Fisheries Survey Summary
10 surveys on file from MN DNR Fisheries. Most recent: 2020-07-21 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluntnose Minnow | 139.42 | — |
| BNS | 63.57 | — |
| SUN | 37.29 | — |
| Largemouth Bass | 21.69 | 0.64 lb |
| Bluegill | 20.42 | 0.17 lb |
| JND | 13.45 | — |
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
Bluegill
From the 2020-07-21 survey
Crystal Lake (11-0502-00) is a 190.20-acre lake with a maximum depth of 40 feet located 5 miles southeast of Akeley, MN. Park Rapids Fisheries staff conducted a survey targeting near shore fish species on July 21, 2020 to assess populations of non-game and small sport fish. Ten 100-foot sampling sites were evenly…
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
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.024 m/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (15 observations).
Estimated open water season: 211 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2007-04-10 (2007) | 2008-04-30 (2008) |
| Ice-In | 2006-11-02 (2006) | 2001-11-28 (2001) |
Most recent ice-out: 2008-04-30
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN11-0502-00 · Official waterbody report
County Ranking
Ranked #28 of 104 lakes in Cass County
Nearby Lakes in Cass County
Frequently asked questions about Crystal Lake
What is the water quality grade for Crystal Lake?
- Crystal Lake in Cass County, Minnesota has a water quality grade of A (Excellent). 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?
- Excellent for swimming, crystal clear water with minimal algae. Crystal Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.3 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Crystal Lake?
- Crystal Lake typically sits around 70°F at the surface in August, 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.
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 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Crystal Lake, Ten Mile Lake. Public access is listed as yes.
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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)
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