Surprise Lake
Surprise Lake in Oconto County, Wisconsin has a water quality grade of B (Good). Water clarity: 8 ft visibility. Phosphorus: 13.1 µg/L. Maximum depth: 20 ft. Surface area: 66 acres.
Wisconsin DNR lists Panfish as common on Surprise Lake. DNR survey details →
- Clarity
- 8 ft
- Max depth
- 20 ft
- Area
- 66 acres
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- Yes
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Surprise Lake is a 66-acre mesotrophic lake in Oconto County, Wisconsin with a maximum depth of 20 feet. Water quality is graded B based on 1 sampling years through 2024. The lake supports 4 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 2 public boat landings. Compared to the 38 other monitored lakes in Oconto County, Surprise Lake ranks #19 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2024-09-05. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyLimited data
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)
Moderate clarity, visible to about 8 ft. Phosphorus level: 13.1 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8 ft | Not graded |
| Phosphorus | 13.1 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Surprise Lake
Compare lakeside cabins, hotels, and vacation rentals near Surprise Lake in Oconto 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 Surprise Lake
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Wisconsin DNR lists Panfish as common on Surprise Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Surprise Lake B from EPA Water Quality Portal chemistry, and the water-quality trend over 7 years of monitoring is stable. 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. 2 stations on file (most recent sample 2024).
Fish Species (DNR-rated)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Surprise Lake covering fish populations, stocking, water quality, and management. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2016Surprise Lake comprehensive survey, 2016Comprehensive Survey · WI DNR · 2016 (PDF)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 20 ft |
| Surface Area | 66 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Surprise Lake - NorthPublic
- Surprise Lake - SouthPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Surprise 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: → Stable
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.151 m/yr | 7 |
| Phosphorus | → Stable | -0.18 µg/L/yr | 7 |
County Ranking
Ranked #19 of 39 lakes in Oconto County
Nearby Lakes in Oconto County
Frequently asked questions about Surprise Lake
Where is Surprise Lake?
- Surprise Lake is a lake in Oconto County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Surprise Lake?
- Surprise Lake in Oconto County, Wisconsin has a water quality grade of B (Good). Water clarity: 8 ft visibility. Phosphorus: 13.1 µg/L. Maximum depth: 20 ft. Surface area: 66 acres.
Is Surprise Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Surprise Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
How deep is Surprise Lake?
- Surprise Lake has a maximum depth of 20 feet. The lake covers 66 acres.
What fish are in Surprise Lake?
- Fish species found in Surprise Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. Surprise Lake is located in Oconto County, Wisconsin.
What did the DNR fisheries survey find at Surprise Lake?
- Wisconsin DNR lists Panfish as common on Surprise Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Surprise Lake B from EPA Water Quality Portal chemistry, and the water-quality trend over 7 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Surprise Lake?
- Surprise Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Surprise Lake - North, Surprise Lake - South. Public access is listed as yes.
Explore Surprise Lake across LakeQuality
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Species activity outlook by water temperature and season
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Moderate nutrients, good water quality
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State Parks Near Surprise Lake
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Mesotrophic Lakes in Wisconsin
Where this data comes from
27 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX27 samples · 2020–2024
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
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