Crystal Lake
Crystal Lake in Dakota County, Minnesota has a water quality grade of C (Fair). Water clarity: 7 ft visibility. Phosphorus: 27 µg/L. Chlorophyll-a (algae): 14.4 µg/L. Maximum depth: 37 ft. Surface area: 293.24 acres.
- Clarity
- 7 ft
- Typical in August
- 73°F
- Max depth
- 37 ft
- Area
- 293 acres
- Type
- Eutrophic
- Trend
- → Stable
- Public access
- Yes
- Ice-out
- Apr 5
- Open water
- 236 days
Next lake in Dakota County
Crystal Lake is a 293-acre productive, nutrient-rich eutrophic lake in Dakota County, Minnesota with a maximum depth of 37 feet (9-foot average). Water quality is graded C based on 2 sampling years through 2025. Water clarity 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. Compared to the 44 other monitored lakes in Dakota County, Crystal Lake ranks #12 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-04. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyModerate
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Moderate clarity, visible to about 7 ft. Phosphorus level: 27 µg/L. Chlorophyll-a: 14.4 µg/L. Trophic State Index: 53.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7 ft | Not graded |
| Phosphorus | 27 µg/L | Fair |
| Chlorophyll-a (Algae) | 14.4 µg/L | Fair |
| Trophic State Index (TSI) | 53 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Crystal Lake
Compare lakeside cabins, hotels, and vacation rentals near Crystal Lake in Dakota 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 73°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 75°F) and coldest in Feb (about 38°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 225 field readings (2010–2025) via the EPA Water Quality Portal. See the full Crystal Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Crystal Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (50,119 cells/mL) on March 13, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 37 ft |
| Average Depth | 9 ft |
| Surface Area | 293 acres |
| Shoreline Length | 6.1 mi |
| Littoral Zone | 71% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Crystal LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Crystal 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
14 surveys on file from MN DNR Fisheries. Most recent: 2025-09-04 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 81.39 | 0.11 lb |
| SUN | 45.19 | — |
| Black Bullhead | 18.25 | 0.54 lb |
| Largemouth Bass | 16.34 | 0.88 lb |
| Hybrid Sunfish | 10.11 | 0.18 lb |
| Green Sunfish | 9.15 | 0.1 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
Black Bullhead
Largemouth Bass
Hybrid Sunfish
From the 2025-09-04 survey
Minnesota DNR Fisheries IBI program staff conducted an assessment of lakeshore habitat on Crystal Lake on September 4th, 2025, following the Score the Shore survey protocols. The assessment consisted of 49 survey sites evenly spaced 70 meters around the lake. Assessments were made in three habitat zones: Shoreline…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Crystal Lake. 3 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
- —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 | ↓ Declining | -0.107 m/yr | 6 |
| Phosphorus | ↑ Improving | -2 µg/L/yr | 3 |
| Chlorophyll-a | → Stable | -0.15 µg/L/yr | 3 |
Ice Season
Historical ice data from Minnesota DNR (84 observations).
Estimated open water season: 236 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-02 (2024) | 2018-04-30 (2018) |
| Ice-In | 1991-11-04 (1991) | 2001-12-20 (2001) |
Most recent ice-out: 2025-03-26
EPA Impairment Status
Crystal 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 MN19-0027-00 · Official waterbody report
County Ranking
Ranked #12 of 45 lakes in Dakota County
Nearby Lakes in Dakota County
Frequently asked questions about Crystal Lake
What is the water quality grade for Crystal Lake?
- Crystal Lake in Dakota County, Minnesota has a water quality grade of C (Fair). Water clarity: 7 ft visibility. Phosphorus: 27 µg/L. Chlorophyll-a (algae): 14.4 µg/L. Maximum depth: 37 ft. Surface area: 293.24 acres.
Is Crystal Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Crystal Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 14.4 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Crystal Lake?
- Crystal Lake typically sits around 73°F at the surface in August, from 225 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Crystal Lake?
- Crystal Lake has a maximum depth of 37 feet and an average depth of 9 feet. The lake covers 293.24 acres.
What fish are in Crystal Lake?
- Fish species found in Crystal Lake include black bullhead, black crappie, bluegill, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, tiger muskellunge, walleye, white sucker, yellow bullhead, yellow perch. Crystal Lake is located in Dakota County, Minnesota.
When does Crystal Lake thaw?
- Crystal Lake typically has ice-out around Apr 5. Ice typically forms around Nov 27. The open water season is approximately 236 days.
Does Crystal Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Crystal Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (50,119 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
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.
Explore Crystal Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Dakota County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Minnesota River Watershed, ranked by water quality
High nutrients, frequent algae, reduced clarity
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Crystal Lake
Other Grade C Lakes in Minnesota
Eutrophic Lakes in Minnesota
Where this data comes from
320 measurements from 3 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
MNPCA320 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Phosphorus by Two Reagent Colorimetry
- Analysis of Chlorophyll in Periphyton and Plankton
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity, Probe Method
Monitoring station identifiers (3)
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