Cedar Island Lake
Cedar Island Lake in St. Louis County, Minnesota has a water quality grade of A (Excellent). Water clarity: 3.8 ft visibility. Phosphorus: 20.5 µg/L. Chlorophyll-a (algae): 3.6 µg/L.
- Clarity
- 3.8 ft
- Typical in August
- 69°F
- Mean depth
- ~9 ft est.
- Type
- Mesotrophic
- Public access
- Yes
Next lake in St. Louis County
Cedar Island Lake is a mesotrophic lake in St. Louis County, Minnesota with an estimated average depth of about 9 feet. Water quality is graded A based on 2 sampling years through 2021. Limited fish-species data available. Public access is available with 1 public boat landing. 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. Grade methodology: LakeGrade methodology.
Watch Cedar Island Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Grade onlyLimited data
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Murky, only visible to about 3.8 ft. Phosphorus level: 20.5 µg/L. Chlorophyll-a: 3.6 µg/L. Trophic State Index: 50.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.8 ft | Not graded |
| Phosphorus | 20.5 µg/L | Good |
| Chlorophyll-a (Algae) | 3.6 µg/L | Good |
| Trophic State Index (TSI) | 50 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Cedar Island Lake
Compare lakeside cabins, hotels, and vacation rentals near Cedar Island Lake in St. Louis County, Minnesota — 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.
Top-rated places to stay near Cedar Island Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Cedar Island Lake typically sits around 69°F at the surface in August. 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.
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
| Characteristic | Value |
|---|---|
| Average Depth | ~9 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Cedar Island 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
- Embarrass Lake (South)Public
Fishing Cedar Island Lake
EPA Impairment Status
Cedar Island 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 MN69-0568-01 · Official waterbody report · Matched by proximity (0.7 km)
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.
County Ranking
Ranked #11 of 68 lakes in St. Louis County
Nearby Lakes in St. Louis County
Frequently asked questions about Cedar Island Lake
What is the water quality grade for Cedar Island Lake?
- Cedar Island Lake in St. Louis County, Minnesota has a water quality grade of A (Excellent). 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?
- Excellent for swimming, crystal clear water with minimal algae. Cedar Island Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 3.6 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Cedar Island Lake?
- Cedar Island Lake typically sits around 69°F at the surface in August, 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 9 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 Cedar Island Lake?
- Cedar Island Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Embarrass Lake (South). Public access is listed as yes.
Explore Cedar Island Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in St. Louis County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Lake Vermilion Area area
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Lake Superior Basin (MN+WI), ranked by water quality
Lakes in the Rainy Lake Watershed, ranked by water quality
Moderate nutrients, good water quality
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Cedar Island Lake
Other Grade A Lakes in Minnesota
Mesotrophic Lakes in Minnesota
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)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory