Crystal Lake
Blue Earth County, Minnesota379 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Crystal Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Impaired biota (cause unknown)
- 8 ft max depth
- Public access
- Limited data
Crystal Lake in Blue Earth County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.5 ft visibility. Phosphorus: 172 µg/L. Chlorophyll-a (algae): 59.9 µg/L. Maximum depth: 8 ft. Surface area: 379.38 acres.
Minnesota DNR's Standard Survey on August 15, 2022 caught 11.00 walleye per gill net at Crystal Lake. Length samples in the latest survey that recorded them ran 9–26 inches. DNR survey details →
Crystal Lake is a 379-acre highly nutrient-loaded hypereutrophic lake in Blue Earth County, Minnesota with a maximum depth of 8 feet (8-foot average). Overall water quality is declining over recent sampling years. The lake supports 12 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 1 public boat landing. Compared to the 4 other monitored lakes in Blue Earth County, Crystal Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-06. Methodology: how these readings are compared.
What Crystal Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing12 species recorded
- Ice seasonIce-out around Apr 1
Swimming conditions
Readings onlyRecreation use not supported
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 5) for impaired biota (cause unknown), nutrients (phosphorus, nitrogen). 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.
Very murky, less than 1.5 ft of visibility. Phosphorus 172 µg/L. Chlorophyll-a 59.9 µg/L. TSI 73.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 172µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 59.9µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 73 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Crystal Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Crystal Lake typically sits around 71°F at the surface in September. Summer average is about 75°F. Usually warmest in Jul (about 77°F) and coldest in May (about 61°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (61°F) to its warmest (77°F).
Typical surface water temperature by month, from 66 field readings (2018–2024) 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 very high (1,584,893 cells/mL) on July 19, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Minnesota DNR's Standard Survey on August 15, 2022 caught 11.00 walleye per gill net at Crystal Lake. Length samples in the latest survey that recorded them ran 9–26 inches.
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 4 years of monitoring is declining. 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: 2023-04-19 (Targeted Survey).
11 surveys on file · most recent 2023-04-19 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Black Bullhead | 109.40 | 5–13 in 2022-08-15 | 0.3 lb |
| Black Crappie | 20.82 | 5–15 in 2022-08-15 | 0.27 lb |
| Walleye | 16.75 | 9–26 in 2022-08-15 | 1.28 lb |
| Common Carp | 12.05 | 20–27 in 2022-08-15 | 3.19 lb |
| Bluegill | 8.82 | 7–8 in 2022-08-15 | 0.25 lb |
| Green Sunfish | 7.00 | 2 in 2001-08-16 | 0.27 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.
Black Bullhead
Black Crappie
Walleye
Common Carp
From the 2023-04-19 survey
Two trap nets were set at Crystal Lake on 19 April 2023 to assess winterkill. Yellow Perch and Black Bullheads were abundant. A single Black Crappie and a single White Sucker were also sampled. We have reports of anglers catching Black Crappie from shore. Dead Common Carp were observed on the 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
Lake Details
Max depth
8 ft
Average depth
8 ft
Surface area
379 acres
Shoreline
5.5 mi
Littoral zone
100%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
40 sq mi
HydroLAKES / HydroSHEDS
Elevation
965 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 Blue Earth 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Crystal Lake are listed below.
Top-rated places to stay near Crystal 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 →
Follow Crystal Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fish Species
Click a species to see every lake where it is documented.
Fishing Crystal Lake
Water Quality Trend: Worsening
Based on 4 years of monitoring (2021–2024).
Water clarity
Worsening4 years
Ice season
Typical ice-out
Apr 1
Earliest Mar 20, 1911 · Latest Apr 14, 2008
Typical ice-in
Nov 20
Earliest Nov 12, 1996 · Latest Dec 1, 2020
Most recent ice-out
Mar 23
2021
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 5).
Causes of impairment
Designated uses not supporting: Aquatic life, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN07-0098-00 · Official waterbody report
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Crystal Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Poet Biorefining - Lake CrystalLake Crystal · 3.7 mi away · NPDES MN0067172Recent violation
- Lake Crystal WwtpLake Crystal · 0.6 mi away · NPDES MN0055981
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Blue Earth County
Frequently asked questions about Crystal Lake
Where is Crystal Lake?
- Crystal Lake is a lake in Blue Earth 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 Blue Earth County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.5 ft visibility. Phosphorus: 172 µg/L. Chlorophyll-a (algae): 59.9 µg/L. Maximum depth: 8 ft. Surface area: 379.38 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 5) for impaired biota (cause unknown), nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Crystal Lake?
- Crystal Lake typically sits around 71°F at the surface in September, from 66 EPA Water Quality Portal field readings (2018–2024). That is a typical value for the month, not a live reading.
How deep is Crystal Lake?
- Crystal Lake has a maximum depth of 8 feet and an average depth of 8 feet. The lake covers 379.38 acres.
What fish are in Crystal Lake?
- Fish species found in Crystal Lake include bigmouth buffalo, black bullhead, black crappie, bluegill, common carp, hybrid sunfish, northern pike, walleye, white crappie, white sucker, yellow bullhead, yellow perch. Crystal Lake is located in Blue Earth County, Minnesota.
What did the DNR fisheries survey find at Crystal Lake?
- Minnesota DNR's Standard Survey on August 15, 2022 caught 11.00 walleye per gill net at Crystal Lake. Length samples in the latest survey that recorded them ran 9–26 inches. 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 4 years of monitoring is declining. 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 1. Ice typically forms around Nov 20. The open water season is approximately 233 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 very high (1,584,893 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.
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
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in Blue Earth County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the Minnesota River Watershed, ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
More lakes in Minnesota
State Parks Near Crystal Lake
Other Lakes in Minnesota
Hypereutrophic Lakes in Minnesota
Where this data comes from
40 measurements from 2 monitoring stations, 2021–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA40 samples · 2021–2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by 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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
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