Gilas Lake
Gilas Lake in Marinette County, Wisconsin has a water quality grade of B (Good). Water clarity: 15 ft visibility. Phosphorus: 12.6 µg/L. Maximum depth: 88 ft. Surface area: 135 acres.
- Clarity
- 15 ft
- Max depth
- 88 ft
- Area
- 135 acres
- Type
- Oligotrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Marinette County
Gilas Lake is a 135-acre cold, clear oligotrophic lake in Marinette County, Wisconsin with a maximum depth of 88 feet. Water quality is graded B based on 1 sampling years through 2026. Overall water quality is improving over recent sampling years. The lake supports 3 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 3 public boat landings. Compared to the 9 other monitored lakes in Marinette County, Gilas Lake ranks #7 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-29. 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)
Crystal clear, you can see 15 ft down. Phosphorus level: 12.6 µg/L. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 15 ft | Not graded |
| Phosphorus | 12.6 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Gilas Lake
Compare lakeside cabins, hotels, and vacation rentals near Gilas Lake in Marinette 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 | 88 ft |
| Surface Area | 135 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Nelligan LakePublic
- Gilas LakePublic
- Murphy LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Gilas 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 2002. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Gilas 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).
- 2022Gilas Lake comprehensive survey, 2022Comprehensive Survey · WI DNR · 2022 (PDF)
Water Quality Trend: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.843 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.41 µg/L/yr | 7 |
County Ranking
Ranked #7 of 10 lakes in Marinette County
Nearby Lakes in Marinette County
Frequently asked questions about Gilas Lake
What is the water quality grade for Gilas Lake?
- Gilas Lake in Marinette County, Wisconsin has a water quality grade of B (Good). Water clarity: 15 ft visibility. Phosphorus: 12.6 µg/L. Maximum depth: 88 ft. Surface area: 135 acres.
Is Gilas Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Gilas Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
How deep is Gilas Lake?
- Gilas Lake has a maximum depth of 88 feet. The lake covers 135 acres.
What fish are in Gilas Lake?
- Fish species found in Gilas Lake include Panfish, Largemouth Bass, Northern Pike. Gilas Lake is located in Marinette County, Wisconsin.
Are there boat ramps on Gilas Lake?
- Gilas Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Nelligan Lake, Gilas Lake, Murphy Lake. Public access is listed as yes.
Explore Gilas Lake across LakeGrade
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Fish species and best lakes in Marinette County
Species activity outlook by water temperature and season
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Low nutrients, clear water, excellent for swimming
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State Parks Near Gilas Lake
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Where this data comes from
40 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_WQX40 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