Spider Lake
Spider Lake in Iron County, Wisconsin has a water quality grade of B (Good). Water clarity: 8.5 ft visibility. Phosphorus: 14.4 µg/L.
- Clarity
- 8.5 ft
- Typical in August
- 69°F
- Mean depth
- ~10 ft est.
- Type
- Mesotrophic
- Trend
- ↓ Declining
- Public access
- Yes
Next lake in Iron County
Spider Lake is a mesotrophic lake in Iron County, Wisconsin with an estimated average depth of about 10 feet. Water quality is graded B based on 1 sampling years through 2026. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 2 public boat landings. Compared to the 15 other monitored lakes in Iron County, Spider Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-30. 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)
Moderate clarity, visible to about 8.5 ft. Phosphorus level: 14.4 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.5 ft | Not graded |
| Phosphorus | 14.4 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Spider Lake
Compare lakeside cabins, hotels, and vacation rentals near Spider Lake in Iron 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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Water Temperature
Spider Lake typically sits around 69°F at the surface in August. Summer average is about 73°F. Usually warmest in Jul (about 76°F) and coldest in May (about 48°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 10 field readings (2024–2026) via the EPA Water Quality Portal. See the full Spider Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~10 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Wisconsin has not published bathymetry for Spider Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Oxbow LakePublic
- Spider LakePublic
Fishing Spider Lake
Water Quality Trend: ↓ Declining
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.187 m/yr | 7 |
| Phosphorus | ↓ Declining | +1.53 µg/L/yr | 6 |
EPA Impairment Status
Spider Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit WI10003764 · Official waterbody report
County Ranking
Ranked #1 of 16 lakes in Iron County
Nearby Lakes in Iron County
Frequently asked questions about Spider Lake
What is the water quality grade for Spider Lake?
- Spider Lake in Iron County, Wisconsin has a water quality grade of B (Good). Water clarity: 8.5 ft visibility. Phosphorus: 14.4 µg/L.
Is Spider Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Spider Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Spider Lake?
- Spider Lake typically sits around 69°F at the surface in August, from 10 EPA Water Quality Portal field readings (2024–2026). That is a typical value for the month, not a live reading.
How deep is Spider Lake?
- No published bathymetric survey covers Spider Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 10 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Spider Lake?
- Spider Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Oxbow Lake, Spider Lake. Public access is listed as yes.
Explore Spider Lake across LakeGrade
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Fish species and best lakes in Iron County
Species activity outlook by water temperature and season
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Moderate nutrients, good water quality
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Other Grade B Lakes in Wisconsin
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Where this data comes from
154 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_WQX154 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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory