Onland Lake
Onland Lake in Portage County, Wisconsin has a water quality grade of B (Good). Water clarity: 10.5 ft visibility. Phosphorus: 12.8 µg/L. Maximum depth: 28 ft. Surface area: 48 acres.
Wisconsin DNR lists Panfish as common on Onland Lake. DNR survey details →
- Clarity
- 10.5 ft
- Typical in August
- 76°F
- Max depth
- 28 ft
- Area
- 48 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
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Onland Lake is a 48-acre mesotrophic lake in Portage County, Wisconsin with a maximum depth of 28 feet. Water quality is graded B based on 1 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 3 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Compared to the 13 other monitored lakes in Portage County, Onland Lake ranks #8 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-10-07. 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 10.5 ft. Phosphorus level: 12.8 µg/L. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.5 ft | Not graded |
| Phosphorus | 12.8 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Onland Lake
Compare lakeside cabins, hotels, and vacation rentals near Onland Lake in Portage 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 Onland Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Water Temperature
Onland Lake typically sits around 76°F at the surface in August. Summer average is about 77°F. Usually warmest in Jul (about 79°F) and coldest in Jan (about 36°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 89 field readings (2024–2025) via the EPA Water Quality Portal. See the full Onland Lake water temperature breakdown →
Wisconsin DNR lists Panfish as common on Onland Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Onland Lake B from EPA Water Quality Portal chemistry, and the water-quality trend over 7 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. Monitored by volunteers since 2013. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 28 ft |
| Surface Area | 48 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 Onland 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: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.377 m/yr | 7 |
| Phosphorus | ↑ Improving | -0.76 µg/L/yr | 6 |
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Onland Lake under Clean Water Act (NPDES) discharge permits.
- Gordondale FarmsAmherst, Town Of · 1.4 mi away · NPDES WI0062359
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 #8 of 14 lakes in Portage County
Nearby Lakes in Portage County
Frequently asked questions about Onland Lake
Where is Onland Lake?
- Onland Lake is a lake in Portage County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Onland Lake?
- Onland Lake in Portage County, Wisconsin has a water quality grade of B (Good). Water clarity: 10.5 ft visibility. Phosphorus: 12.8 µg/L. Maximum depth: 28 ft. Surface area: 48 acres.
Is Onland Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Onland Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Onland Lake?
- Onland Lake typically sits around 76°F at the surface in August, from 89 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Onland Lake?
- Onland Lake has a maximum depth of 28 feet. The lake covers 48 acres.
What fish are in Onland Lake?
- Fish species found in Onland Lake include Panfish, Largemouth Bass, Northern Pike. Onland Lake is located in Portage County, Wisconsin.
What did the DNR fisheries survey find at Onland Lake?
- Wisconsin DNR lists Panfish as common on Onland Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Onland Lake B from EPA Water Quality Portal chemistry, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Explore Onland Lake across LakeQuality
Fish species and top-graded lakes across Wisconsin
Fish species and best lakes in Portage County
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its grade
Moderate nutrients, good water quality
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State Parks Near Onland Lake
Other Grade B Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
Where this data comes from
63 measurements from 1 monitoring station, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX63 samples · 2021–2025
Analytical methods
- Phosphorus by Colorimetry
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes