Black Hawk Lake
Black Hawk Lake in Iowa County, Wisconsin has a water quality grade of B (Good). Water clarity: 5 ft visibility. Phosphorus: 19.9 µg/L. Maximum depth: 42 ft. Surface area: 212 acres.
- Clarity
- 5 ft
- Max depth
- 42 ft
- Area
- 212 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
Next lake in Iowa County
Black Hawk Lake is a 212-acre productive, nutrient-rich eutrophic lake in Iowa County, Wisconsin with a maximum depth of 42 feet. Water quality is graded B based on 1 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 4 documented fish species including Panfish, Largemouth Bass, and Smallmouth Bass. Public access is available with 1 public boat landing. Compared to the 5 other monitored lakes in Iowa County, Black Hawk Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-08-20. 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)
Murky, only visible to about 5 ft. Phosphorus level: 19.9 µg/L. Trophic State Index: 51.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | Not graded |
| Phosphorus | 19.9 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 51 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Black Hawk Lake
Compare lakeside cabins, hotels, and vacation rentals near Black Hawk Lake in Iowa 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 | 42 ft |
| Surface Area | 212 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Blackhawk Lake Recreation AreaPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Black Hawk 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. Monitored by volunteers since 1997. 3 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -1.575 m/yr | 4 |
| Phosphorus | ↓ Declining | +3.06 µg/L/yr | 6 |
Reservoir Info (USACE NID)
Black Hawk Lake is a man-made reservoir impounded by the Blackhawk Lake (completed 1969), built primarily for recreation on the OTTER CREEK & CAVE HOLLOW BR; earth-type dam, 50 ft tall and 1,130 ft long.
- Surface area
- 220 ac
- Normal storage
- 3,810 ac-ft
- Max storage
- 7,900 ac-ft
- Drainage area
- 16.1 sq mi
- Hazard class
- Low
- Owner
- Iowa County
Source: USACE National Inventory of Dams, NID ID WI00014 · Operator website
EPA Impairment Status
Black Hawk 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 WI10002617 · Official waterbody report
County Ranking
Ranked #1 of 6 lakes in Iowa County
Nearby Lakes in Iowa County
Frequently asked questions about Black Hawk Lake
What is the water quality grade for Black Hawk Lake?
- Black Hawk Lake in Iowa County, Wisconsin has a water quality grade of B (Good). Water clarity: 5 ft visibility. Phosphorus: 19.9 µg/L. Maximum depth: 42 ft. Surface area: 212 acres.
Is Black Hawk Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Black Hawk Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
How deep is Black Hawk Lake?
- Black Hawk Lake has a maximum depth of 42 feet. The lake covers 212 acres.
What fish are in Black Hawk Lake?
- Fish species found in Black Hawk Lake include Panfish, Largemouth Bass, Smallmouth Bass, Walleye. Black Hawk Lake is located in Iowa County, Wisconsin.
Are there boat ramps on Black Hawk Lake?
- Black Hawk Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Blackhawk Lake Recreation Area. Public access is listed as yes.
Explore Black Hawk Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
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Fish species and best lakes in Iowa County
Species activity outlook by water temperature and season
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High nutrients, frequent algae, reduced clarity
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State Parks Near Black Hawk Lake
Other Grade B Lakes in Wisconsin
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Where this data comes from
49 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX49 samples · 2020–2025
Analytical methods
- Phosphorus by Colorimetry
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)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory