Big Round Lake
Polk County, Wisconsin1,014 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Big Round Lake. Here is what has been measured.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- Curly-Leaf Pondweed
- 17 ft max depth
- Public access
Big Round Lake in Polk County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 5 ft visibility. Phosphorus: 27 µg/L. Chlorophyll-a (algae): 6.9 µg/L. Maximum depth: 17 ft. Surface area: 1014 acres.
Wisconsin DNR rates Panfish as abundant on Big Round Lake. DNR survey details →
Big Round Lake is a 1,014-acre productive, nutrient-rich eutrophic lake in Polk County, Wisconsin with a maximum depth of 17 feet. Overall water quality is improving over recent sampling years. The lake supports 5 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available with 1 public boat landing. Compared to the 54 other monitored lakes in Polk County, Big Round Lake ranks #28 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-21. Methodology: how these readings are compared.
Big Round Lake covers about 1,000 acres in Polk County. It has one public boat landing. Vrbo is where to look for cabins and lake homes around Big Round Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Big Round Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing5 species recorded
- Big water1,014 acres
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. Big Round Lake is listed impaired under Clean Water Act §303(d) (IR 5R) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Big Round Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Big Round Lake
These are the measurements Wisconsin DNR publishes for Big Round Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 5 ft. Phosphorus 27 µg/L. Chlorophyll-a 6.9 µg/L. TSI 52.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 27µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 6.9µg/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. | 52 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Big Round Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Big Round Lake typically sits around 50°F at the surface in October. Summer average is about 74°F. Usually warmest in Jul (about 78°F) and coldest in Apr (about 50°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (50°F) to its warmest (78°F).
Typical surface water temperature by month, from 140 field readings (2024–2025) via the EPA Water Quality Portal. See the full Big Round Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Big Round Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (26,546 cells/mL) on October 25, 2025.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Wisconsin DNR rates Panfish as abundant on Big Round Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Big Round Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1992. 2 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
17 ft
Surface area
1,014 acres
Public access
Yes
Listed by Wisconsin DNR
Recreation & Access
- Big Round 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 Big Round Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Round Lake in Polk County, Wisconsin — 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 Big Round Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Big Round 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.
Water Quality Trend: Improving
Based on 7 years of monitoring (2020–2026).
Water clarity
Improving6 years
Phosphorus
Improving-8.95 µg/L/yr7 years
Chlorophyll-a
Improving-12.08 µg/L/yr6 years
EPA Impairment Status
Big Round Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5R).
Causes of impairment
Designated uses not supporting: Aquatic life, Recreation.
Source: EPA ATTAINS assessment unit WI10005037 · Official waterbody report
Nearby Lakes in Polk County
Frequently asked questions about Big Round Lake
Where is Big Round Lake?
- Big Round Lake is a lake in Polk County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Big Round Lake?
- Big Round Lake in Polk County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 5 ft visibility. Phosphorus: 27 µg/L. Chlorophyll-a (algae): 6.9 µg/L. Maximum depth: 17 ft. Surface area: 1014 acres.
Is Big Round Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Big Round Lake is listed impaired under Clean Water Act §303(d) (IR 5R) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Big Round Lake?
- Big Round Lake typically sits around 50°F at the surface in October, from 140 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Big Round Lake?
- Big Round Lake has a maximum depth of 17 feet. The lake covers 1014 acres.
What fish are in Big Round Lake?
- Fish species found in Big Round Lake include Musky, Panfish, Largemouth Bass, Northern Pike, Walleye. Big Round Lake is located in Polk County, Wisconsin.
What did the DNR fisheries survey find at Big Round Lake?
- Wisconsin DNR rates Panfish as abundant on Big Round Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Big Round Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Does Big Round Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Big Round Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (26,546 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Are there boat ramps on Big Round Lake?
- Big Round Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Big Round Lake. Public access is listed as yes.
Can I fish at Big Round Lake?
- Big Round 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 Wisconsin's fish and wildlife agency, so check its current regulations before you go.
Explore Big Round Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Wisconsin
Fish species and best lakes in Polk County
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its readings
Lakes in the St. Croix Watershed, ranked by water quality
Wisconsin's cleanest lakes, ranked on agency measurements
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Compare Big Round Lake With Nearby Lakes
Where this data comes from
606 measurements from 3 monitoring stations, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- St. Croix Chippewa Indians of Wisconsin
STCROIX_WQX342 samples · 2020–2025 - Wisconsin Department of Natural Resources
WIDNR_WQX264 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 4500 P F ~ Phosphorus in Water by Colorimetry Automated Ascorbic Acid Method
- 10200 H ~ Chlorophyll a-b-c Determination
- Calculation
Monitoring station identifiers (3)
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
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory