Billy Boy Flowage Lake
Sawyer County, Wisconsin221 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Billy Boy Flowage Lake. Here is what has been measured.
- Mesotrophic
- Curly-Leaf Pondweed
- 46 ft max depth
Billy Boy Flowage Lake in Sawyer County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Phosphorus: 16 µg/L. Maximum depth: 46 ft. Surface area: 221 acres.
Wisconsin DNR lists Northern Pike as common on Billy Boy Flowage Lake. DNR survey details →
Billy Boy Flowage Lake is a 221-acre mesotrophic lake in Sawyer County, Wisconsin with a maximum depth of 46 feet. Overall water quality is improving over recent sampling years. The lake supports 6 documented fish species including Musky, Panfish, and Largemouth Bass. Compared to the 44 other monitored lakes in Sawyer County, Billy Boy Flowage Lake ranks #31 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2024-08-27. Methodology: how these readings are compared.
Billy Boy Flowage Lake covers about 220 acres in Sawyer County. For a place on the water, look through cabin and lake-house rentals near Billy Boy Flowage Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Billy Boy Flowage Lake is good for
From access and monitoring records, not editorial picks.
- Fishing6 species recorded
- Deep water46 ft surveyed max depth
Swimming conditions
Readings onlyLow algae
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. Check local advisories before you swim.
Whether Billy Boy Flowage 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 Billy Boy Flowage Lake
These are the measurements Wisconsin DNR publishes for Billy Boy Flowage Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Phosphorus 16 µg/L. TSI 44.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | 16µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 44 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Billy Boy Flowage Lake
Answers come straight from the public measurements and survey records on this page.
Wisconsin DNR lists Northern Pike as common on Billy Boy Flowage Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Billy Boy Flowage Lake’s water-quality measurements separately, and the water-quality trend over 5 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. 1 station on file (most recent sample 2024).
Fish Species (DNR-rated)
Lake Details
Max depth
46 ft
Surface area
221 acres
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Stays near Billy Boy Flowage Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Billy Boy Flowage Lake
- → Billy Boy Flowage Lake fishing: DNR survey catch rates, species & stocking
- → Billy Boy Flowage Lake fishing forecast & best times (species outlook + 14-day solunar calendar)
- → Billy Boy Flowage Lake fishing regulations (limits, seasons, special rules)
- → Is it safe to eat fish from Billy Boy Flowage Lake? (mercury & PFAS guide)
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 5 years of monitoring (2020–2024).
Water clarity
Improving5 years
Phosphorus
Worsening+0.35 µg/L/yr5 years
Chlorophyll-a
Improving-0.07 µg/L/yr4 years
Reservoir Info (USACE NID)
Billy Boy Flowage Lake is a man-made reservoir impounded by the Billy Boy (completed 1936), built primarily for recreation on the COUDERAY; gravity-type dam, 13 ft tall and 40 ft long.
- Surface area
- 8,464 ac
- Normal storage
- 28,300 ac-ft
- Max storage
- 53,600 ac-ft
- Drainage area
- 110 sq mi
- Hazard class
- Significant
- Owner
- Sawyer County
Source: USACE National Inventory of Dams, NID ID WI00305 · Operator website
Nearby Lakes in Sawyer County
Frequently asked questions about Billy Boy Flowage Lake
Where is Billy Boy Flowage Lake?
- Billy Boy Flowage Lake is a lake in Sawyer County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Billy Boy Flowage Lake?
- Billy Boy Flowage Lake in Sawyer County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Phosphorus: 16 µg/L. Maximum depth: 46 ft. Surface area: 221 acres.
Is Billy Boy Flowage Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Billy Boy Flowage Lake?
- Billy Boy Flowage Lake has a maximum depth of 46 feet. The lake covers 221 acres.
What fish are in Billy Boy Flowage Lake?
- Fish species found in Billy Boy Flowage Lake include Musky, Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye. Billy Boy Flowage Lake is located in Sawyer County, Wisconsin.
What did the DNR fisheries survey find at Billy Boy Flowage Lake?
- Wisconsin DNR lists Northern Pike as common on Billy Boy Flowage Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Billy Boy Flowage Lake’s water-quality measurements separately, and the water-quality trend over 5 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Explore Billy Boy Flowage Lake across LakeQuality
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Where this data comes from
21 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Lac Courte Oreilles (Tribal)
LCOWIS_WQX21 samples · 2020–2024
Analytical methods
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 4500 P F ~ Phosphorus in Water by Colorimetry Automated Ascorbic Acid Method
- 2320 B ~ Alkalinity by Gran Titration
- 4500 P E ~ Phosphorus by Ascorbic Acid
Monitoring station identifiers (1)
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
Fish and recreation data from Wisconsin DNR Lakes