Little Cosgrove Lake
Little Cosgrove Lake in Florence County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8.6 ft visibility.
- Clarity
- 8.6 ft
- Mean depth
- ~14 ft est.
- Trend
- ↓ Declining
- Public access
- Yes
Next lake in Florence County
Why Little Cosgrove Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Little Cosgrove Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by WI DNR and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Little Cosgrove Lake is a lake in Florence County, Wisconsin with an estimated average depth of about 14 feet. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-08-20. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Little Cosgrove Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Moderate clarity, visible to about 8.6 ft. Trophic State Index: 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.6 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Little Cosgrove Lake
Compare lakeside cabins, hotels, and vacation rentals near Little Cosgrove Lake in Florence 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 |
|---|---|
| Average Depth | ~14 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Wisconsin has not published bathymetry for Little Cosgrove 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
- Cosgrove & Round LakePublic
Fishing Little Cosgrove Lake
Water Quality Trend: ↓ Declining
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.251 m/yr | 3 |
Nearby Lakes in Florence County
Frequently asked questions about Little Cosgrove Lake
What is the water quality grade for Little Cosgrove Lake?
- Little Cosgrove Lake in Florence County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8.6 ft visibility.
Is Little Cosgrove Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Little Cosgrove Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
How deep is Little Cosgrove Lake?
- No published bathymetric survey covers Little Cosgrove Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 14 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 Little Cosgrove Lake?
- Little Cosgrove Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Cosgrove & Round Lake. Public access is listed as yes.
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Where this data comes from
3 measurements from 2 monitoring stations, 2022–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX3 samples · 2022–2025
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)
Named boat-access points from the USGS National Boat Ramps inventory