Cedar Island Lake
St. Louis County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Cedar Island Lake. Here is what has been measured.
- Mesotrophic
- 21 ft max depth
- Public access
- Limited data
Cedar Island Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3.8 ft visibility. Phosphorus: 20.5 µg/L. Chlorophyll-a (algae): 3.6 µg/L.
Cedar Island Lake is a mesotrophic lake in St. Louis County, Minnesota with an estimated average depth of about 21 feet. Limited fish-species data available. Public access is available. Compared to the 67 other monitored lakes in St. Louis County, Cedar Island Lake ranks #11 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2021-09-27. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Cedar Island Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Cedar Island Lake
These are the measurements Minnesota PCA publishes for Cedar Island Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 3.8 ft. Phosphorus 20.5 µg/L. Chlorophyll-a 3.6 µg/L. TSI 50.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 20.5µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 3.6µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 50 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Cedar Island Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Cedar Island Lake typically sits around 63°F at the surface in September. Summer average is about 70°F. Usually warmest in Jul (about 72°F) and coldest in May (about 56°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (56°F) to its warmest (72°F).
Typical surface water temperature by month, from 45 field readings (2019–2021) via the EPA Water Quality Portal. See the full Cedar Island Lake water temperature breakdown →
Lake Details
Max depth
~21 ft est.
Public access
Yes
Listed by Minnesota PCA
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for Cedar Island Lake.
Lake Size & Watershed
Watershed (drainage) area
167 sq mi
HydroLAKES / HydroSHEDS
Surface area
42 acres
HydroLAKES / HydroSHEDS
Shoreline
1.5 mi
HydroLAKES / HydroSHEDS
Elevation
1,352 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 Cedar Island Lake
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Top-rated places to stay near Cedar Island Lake
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Fishing Cedar Island Lake
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Cedar Island Lake under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Biwabik WwtpBiwabik · 1.2 mi away · NPDES MN0053279Recent violation
- Dyno Nobel IncBiwabik · 1.7 mi away · NPDES MN0060704Recent violation
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 St. Louis County
Frequently asked questions about Cedar Island Lake
Where is Cedar Island Lake?
- Cedar Island Lake is a lake in St. Louis County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Cedar Island Lake?
- Cedar Island Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3.8 ft visibility. Phosphorus: 20.5 µg/L. Chlorophyll-a (algae): 3.6 µg/L.
Is Cedar Island Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Cedar Island Lake?
- Cedar Island Lake typically sits around 63°F at the surface in September, from 45 EPA Water Quality Portal field readings (2019–2021). That is a typical value for the month, not a live reading.
How deep is Cedar Island Lake?
- No published bathymetric survey covers Cedar Island Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 21 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 Cedar Island Lake?
- Public access to Cedar Island Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
24 measurements from 2 monitoring stations, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA24 samples · 2021
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (2)
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)
Lake details from Minnesota DNR LakeFinder