Billy Boy Flowage Lake
Billy Boy Flowage Lake in Sawyer County, Wisconsin has a water quality grade of B (Good). Phosphorus: 16 µg/L. Maximum depth: 46 ft. Surface area: 221 acres.
- Max depth
- 46 ft
- Area
- 221 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
Next lake in Sawyer County
Billy Boy Flowage Lake is a 221-acre mesotrophic lake in Sawyer County, Wisconsin with a maximum depth of 46 feet. Water quality is graded B based on 1 sampling years through 2024. 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. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
No clarity data. Phosphorus level: 16 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 16 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Billy Boy Flowage Lake
Compare lakeside cabins, hotels, and vacation rentals near Billy Boy Flowage Lake in Sawyer 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.
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 46 ft |
| Surface Area | 221 acres |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Billy Boy Flowage 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.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 1 station on file (most recent sample 2024).
Fish Species (DNR-rated)
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.45 m/yr | 5 |
| Phosphorus | ↓ Declining | +0.35 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -0.07 µg/L/yr | 4 |
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
County Ranking
Ranked #31 of 45 lakes in Sawyer County
Nearby Lakes With Higher Grades
Billy Boy Flowage Lake holds Grade B. 3 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 Sawyer County
Frequently asked questions about Billy Boy Flowage Lake
What is the water quality grade for Billy Boy Flowage Lake?
- Billy Boy Flowage Lake in Sawyer County, Wisconsin has a water quality grade of B (Good). Phosphorus: 16 µg/L. Maximum depth: 46 ft. Surface area: 221 acres.
Is Billy Boy Flowage Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Billy Boy Flowage Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
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.
Explore Billy Boy Flowage Lake across LakeGrade
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Moderate nutrients, good water quality
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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)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes