Bass Lake
Bass Lake in St. Croix County, Wisconsin has a water quality grade of B (Good). Water clarity: 10 ft visibility. Phosphorus: 14 µg/L.
- Clarity
- 10 ft
- Typical in August
- 77°F
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- Yes
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Bass Lake is a mesotrophic lake in St. Croix County, Wisconsin. Water quality is graded B based on 1 sampling years through 2026. Water clarity is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 4 other monitored lakes in St. Croix County, Bass Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-04-22. Grade methodology: LakeQuality 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)
Good clarity, visible to about 10 ft. Phosphorus level: 14 µg/L. Trophic State Index: 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10 ft | Not graded |
| Phosphorus | 14 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Bass Lake
Compare lakeside cabins, hotels, and vacation rentals near Bass Lake in St. Croix 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 Bass Lake
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Water Temperature
Bass Lake typically sits around 77°F at the surface in August. Summer average is about 76°F. Usually warmest in Jul (about 79°F) and coldest in Sep (about 70°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 33 field readings (2024–2025) via the EPA Water Quality Portal. See the full Bass Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Bass Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (205,116 cells/mL) on April 11, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Recreation & Access
- Bass LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Bass Lake
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.246 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.8 µg/L/yr | 6 |
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Bass Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Somerset Wastewater Treatment FacilitySomerset · 3 mi away · NPDES WI0030252Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
County Ranking
Ranked #2 of 5 lakes in St. Croix County
Nearby Lakes in St. Croix County
Frequently asked questions about Bass Lake
Where is Bass Lake?
- Bass Lake is a lake in St. Croix County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Bass Lake?
- Bass Lake in St. Croix County, Wisconsin has a water quality grade of B (Good). Water clarity: 10 ft visibility. Phosphorus: 14 µg/L.
Is Bass Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Bass Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Bass Lake?
- Bass Lake typically sits around 77°F at the surface in August, from 33 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
Does Bass Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Bass Lake (clouds, ice, or an off-season gap). The most recent reading was high (205,116 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Are there boat ramps on Bass Lake?
- Bass Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Bass Lake. Public access is listed as yes.
Explore Bass Lake across LakeQuality
4.3 mi away · 45 ft
Fish species and top-graded lakes across Wisconsin
Fish species and best lakes in St. Croix County
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its grade
Lakes in the St. Croix Watershed, ranked by water quality
Moderate nutrients, good water quality
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More Wisconsin Lake Rankings
State Parks Near Bass Lake
Other Grade B Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
Where this data comes from
99 measurements from 2 monitoring stations, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX99 samples · 2020–2026
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory