Willmar Lake
Willmar Lake in Kandiyohi County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 2 ft visibility. Phosphorus: 73 µg/L. Chlorophyll-a (algae): 27.6 µg/L. Maximum depth: 14 ft. Surface area: 636.44 acres.
- Clarity
- 2 ft
- Typical in August
- 76°F
- Max depth
- 14 ft
- Area
- 636 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Mar 28
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Willmar Lake →
Next lake in Kandiyohi County
Willmar Lake is a 636-acre productive, nutrient-rich eutrophic lake in Kandiyohi County, Minnesota with a maximum depth of 14 feet. Water quality is graded D based on 2 sampling years through 2022. Overall water quality is declining over recent sampling years. The lake supports 18 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 2 public boat landings. Compared to the 24 other monitored lakes in Kandiyohi County, Willmar Lake ranks #17 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-06-21. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyAlgae risk
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.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 2 ft of visibility. Phosphorus level: 73 µg/L. Chlorophyll-a: 27.6 µg/L. Trophic State Index: 66.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | Not graded |
| Phosphorus | 73 µg/L | Poor |
| Chlorophyll-a (Algae) | 27.6 µg/L | Poor |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Willmar Lake
Compare lakeside cabins, hotels, and vacation rentals near Willmar Lake in Kandiyohi 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 grade measures nutrients and algae, not lodging — cabins and rentals around Willmar Lake are listed below.
Top-rated places to stay near Willmar Lake
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 →
Water Temperature
Willmar Lake typically sits around 76°F at the surface in August. Summer average is about 77°F. Usually warmest in Jul (about 80°F) and coldest in May (about 67°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 55 field readings (2021–2022) via the EPA Water Quality Portal. See the full Willmar Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 14 ft |
| Surface Area | 636 acres |
| Shoreline Length | 7.9 mi |
| Littoral Zone | 70% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Robbins IslandPublic
- Willmar LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Willmar 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
13 surveys on file from MN DNR Fisheries. Most recent: 2025-07-23 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 113.40 | 0.44 lb |
| Walleye | 31.95 | 1.05 lb |
| Black Crappie | 14.53 | 0.34 lb |
| Freshwater Drum | 13.49 | 1 lb |
| Bluegill | 5.02 | 0.21 lb |
| Yellow Perch | 5.02 | 0.14 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.
Black Bullhead
Walleye
Black Crappie
Freshwater Drum
From the 2025-07-23 survey
A standard survey was conducted on Willmar Lake during late July of 2025. A fall night electrofishing survey was conducted for young of year "YOY" (fingerling sized) Walleye during early September of 2025. A targeted survey is generally used for sampling a specific kind of fish or time of year (i.e. spawning season,…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Willmar Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — WillmarFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — WillmarFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — WillmarPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | 0 m/yr | 3 |
| Phosphorus | ↓ Declining | +17.25 µg/L/yr | 3 |
| Chlorophyll-a | ↓ Declining | +5.75 µg/L/yr | 3 |
Ice Season
Historical ice data from Minnesota DNR (9 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2017-03-07 (2017) | 2018-04-29 (2018) |
| Ice-In | 2007-11-23 (2007) | 2006-11-30 (2006) |
Most recent ice-out: 2021-03-26
EPA Impairment Status
Willmar Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MN34-0180-01 · Official waterbody report · Matched by proximity (0.79 km)
County Ranking
Ranked #17 of 25 lakes in Kandiyohi County
Nearby Lakes With Higher Grades
Willmar Lake holds Grade D. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Kandiyohi County
Frequently asked questions about Willmar Lake
What is the water quality grade for Willmar Lake?
- Willmar Lake in Kandiyohi County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 2 ft visibility. Phosphorus: 73 µg/L. Chlorophyll-a (algae): 27.6 µg/L. Maximum depth: 14 ft. Surface area: 636.44 acres.
Is Willmar Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Willmar Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 27.6 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Willmar Lake?
- Willmar Lake typically sits around 76°F at the surface in August, from 55 EPA Water Quality Portal field readings (2021–2022). That is a typical value for the month, not a live reading.
How deep is Willmar Lake?
- Willmar Lake has a maximum depth of 14 feet. The lake covers 636.44 acres.
What fish are in Willmar Lake?
- Fish species found in Willmar Lake include bigmouth buffalo, black bullhead, black crappie, bluegill, brown bullhead, common carp, freshwater drum, hybrid sunfish, largemouth bass, northern pike, orangespotted sunfish, pumpkinseed, river carpsucker, shortnose gar, walleye, white sucker, yellow bullhead, yellow perch. Willmar Lake is located in Kandiyohi County, Minnesota.
When does Willmar Lake thaw?
- Willmar Lake typically has ice-out around Mar 28.
Are there boat ramps on Willmar Lake?
- Willmar Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Robbins Island, Willmar Lake. Public access is listed as yes.
Explore Willmar Lake across LakeGrade
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Species activity outlook by water temperature and season
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Where this data comes from
64 measurements from 2 monitoring stations, 2020–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA64 samples · 2020–2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2120 B ~ Color in Water by Visual Comparison
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