Hat Rapids Flowage Lake
Oneida County, Wisconsin295 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Hat Rapids Flowage Lake. Here is what has been measured.
- 47 ft max depth
- Limited data
Hat Rapids Flowage Lake in Oneida County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 3.5 ft visibility. Surface area: 295 acres.
Hat Rapids Flowage Lake is a 295-acre lake in Oneida County, Wisconsin with an estimated average depth of about 47 feet. Overall water quality is declining over recent sampling years. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2023-08-06. Methodology: how these readings are compared.
What Hat Rapids Flowage Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Hat Rapids 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 Hat Rapids Flowage Lake
These are the measurements Wisconsin DNR publishes for Hat Rapids Flowage 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 3.5 ft. TSI 59.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| 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. | 59 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Hat Rapids Flowage Lake
Answers come straight from the public measurements and survey records on this page.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 4 stations on file (most recent sample 2023).
Lake Details
Max depth
~47 ft est.
Surface area
295 acres
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Wisconsin has not published bathymetry for Hat Rapids Flowage Lake.
Lake Size & Watershed
Watershed (drainage) area
1,158 sq mi
HydroLAKES / HydroSHEDS
Shoreline
10.9 mi
HydroLAKES / HydroSHEDS
Elevation
1,522 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Wisconsin River - Camp 10 RoadSemi-private
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
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Stays near Hat Rapids Flowage Lake
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Fishing Hat Rapids 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.
Water Quality Trend: Worsening
Based on 4 years of monitoring (2020–2023).
Water clarity
Worsening4 years
Reservoir Info (USACE NID)
Hat Rapids Flowage Lake is a man-made reservoir impounded by the Hat Rapids (completed 1923), built primarily for hydroelectric on the Wisconsin River; gravity-type dam, 30 ft tall and 1,004 ft long.
- Surface area
- 640 ac
- Normal storage
- 4,750 ac-ft
- Max storage
- 4,750 ac-ft
- Drainage area
- 1,143 sq mi
- Hazard class
- High
- Owner
- Wisconsin Public Service Corporation
All listed purposes: Hydroelectric;Recreation.
Source: USACE National Inventory of Dams, NID ID WI00770 · Operator website
Nearby Lakes in Oneida County
Frequently asked questions about Hat Rapids Flowage Lake
Where is Hat Rapids Flowage Lake?
- Hat Rapids Flowage Lake is a lake in Oneida County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Hat Rapids Flowage Lake?
- Hat Rapids Flowage Lake in Oneida County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 3.5 ft visibility. Surface area: 295 acres.
Is Hat Rapids Flowage Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Hat Rapids Flowage Lake?
- No published bathymetric survey covers Hat Rapids Flowage Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 47 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 295 acres.
Are there boat ramps on Hat Rapids Flowage Lake?
- Hat Rapids Flowage Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Wisconsin River - Camp 10 Road.
Can I fish at Hat Rapids Flowage Lake?
- Hat Rapids Flowage 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 Hat Rapids Flowage Lake across LakeQuality
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Where this data comes from
25 measurements from 1 monitoring station, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX25 samples · 2020–2023
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory