Diamond Lake
Polk County, WisconsinView mapDirections
Wisconsin DNR publishes the water-quality measurements for Diamond Lake. Here is what has been measured.
- 42 ft max depth
- Public access
- Limited data
Diamond Lake in Polk County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 8.2 ft visibility.
Diamond Lake is a lake in Polk County, Wisconsin with an estimated average depth of about 42 feet. Limited fish-species data available. Public access is available.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2020-07-07. Methodology: how these readings are compared.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Diamond Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Diamond Lake
These are the measurements Wisconsin DNR publishes for Diamond Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 8.2 ft. TSI 47.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 8.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 47 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Diamond Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~42 ft est.
Public access
Yes
Listed by Wisconsin DNR
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Wisconsin has not published bathymetry for Diamond Lake.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Surface area
109 acres
HydroLAKES / HydroSHEDS
Shoreline
2.3 mi
HydroLAKES / HydroSHEDS
Elevation
988 ft
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.
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Stays near Diamond Lake
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Fishing Diamond Lake
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Diamond Lake under Clean Water Act (NPDES) discharge permits.
- Frederic Village OfFrederic, Village Of · 4.9 mi away · NPDES WI0029254
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Polk County
Frequently asked questions about Diamond Lake
Where is Diamond Lake?
- Diamond Lake is a lake in Polk County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Diamond Lake?
- Diamond Lake in Polk County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 8.2 ft visibility.
Is Diamond Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Diamond Lake?
- No published bathymetric survey covers Diamond Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 42 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Can I fish at Diamond Lake?
- Public access to Diamond Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
1 measurement from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX1 sample · 2020
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)