Big Portage Lake
Big Portage Lake in Vilas County, Wisconsin has a water quality grade of B (Good). Water clarity: 18.5 ft visibility. Phosphorus: 12 µg/L. Maximum depth: 40 ft. Surface area: 586 acres.
Wisconsin DNR lists Smallmouth Bass as common on Big Portage Lake. DNR survey details →
- Clarity
- 18.5 ft
- Typical in August
- 70°F
- Max depth
- 40 ft
- Area
- 586 acres
- Type
- Oligotrophic
- Trend
- → Stable
- Public access
- Yes
Next lake in Vilas County
Swipe left or right on this bar to open the next or previous lake.
Big Portage Lake is a 586-acre cold, clear oligotrophic lake in Vilas County, Wisconsin with a maximum depth of 40 feet. Water quality is graded B based on 1 sampling years through 2026. Water clarity is improving 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 102 other monitored lakes in Vilas County, Big Portage Lake ranks #33 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-19. Grade methodology: LakeQuality methodology.
Watch Big Portage Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
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)
Crystal clear, you can see 18.5 ft down. Phosphorus level: 12 µg/L. Trophic State Index: 38.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 18.5 ft | Not graded |
| Phosphorus | 12 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 38 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Big Portage Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Portage Lake in Vilas 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 Big Portage Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Water Temperature
Big Portage Lake typically sits around 70°F at the surface in August. Summer average is about 71°F. Usually warmest in Jul (about 74°F) and coldest in May (about 61°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 36 field readings (2024–2026) via the EPA Water Quality Portal. See the full Big Portage Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Big Portage Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (82,414 cells/mL) on April 25, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Wisconsin DNR lists Smallmouth Bass as common on Big Portage Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Big Portage 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. Monitored by volunteers since 1991. 2 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 40 ft |
| Surface Area | 586 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Big Portage LakePublic
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 Big Portage 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 | ↑ Improving | +0.455 m/yr | 7 |
| Phosphorus | ↓ Declining | +2.88 µg/L/yr | 6 |
County Ranking
Ranked #33 of 103 lakes in Vilas County
Nearby Lakes in Vilas County
Frequently asked questions about Big Portage Lake
Where is Big Portage Lake?
- Big Portage Lake is a lake in Vilas County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Big Portage Lake?
- Big Portage Lake in Vilas County, Wisconsin has a water quality grade of B (Good). Water clarity: 18.5 ft visibility. Phosphorus: 12 µg/L. Maximum depth: 40 ft. Surface area: 586 acres.
Is Big Portage Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Big Portage Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Big Portage Lake?
- Big Portage Lake typically sits around 70°F at the surface in August, from 36 EPA Water Quality Portal field readings (2024–2026). That is a typical value for the month, not a live reading.
How deep is Big Portage Lake?
- Big Portage Lake has a maximum depth of 40 feet. The lake covers 586 acres.
What fish are in Big Portage Lake?
- Fish species found in Big Portage Lake include Panfish, Largemouth Bass, Smallmouth Bass, Walleye. Big Portage Lake is located in Vilas County, Wisconsin.
What did the DNR fisheries survey find at Big Portage Lake?
- Wisconsin DNR lists Smallmouth Bass as common on Big Portage Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Big Portage 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.
Does Big Portage Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Big Portage Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (82,414 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Are there boat ramps on Big Portage Lake?
- Big Portage Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Big Portage Lake. Public access is listed as yes.
Explore Big Portage Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded lakes across Wisconsin
Fish species and best lakes in Vilas County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Northwoods Wisconsin area
Where to stay at Wisconsin's top lakes, each with its grade
Lakes in the Wisconsin River Watershed, ranked by water quality
Low nutrients, clear water, excellent for swimming
Wisconsin's cleanest and most-polluted lakes, ranked
More Wisconsin Lake Rankings
Other Grade B Lakes in Wisconsin
Oligotrophic Lakes in Wisconsin
Compare Big Portage Lake With Nearby Lakes
Where this data comes from
167 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_WQX167 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
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