Ash Lake
Ash Lake in St. Louis County, Minnesota has a water quality grade of C (Fair). Water clarity: 5.5 ft visibility. Phosphorus: 39 µg/L. Chlorophyll-a (algae): 11.1 µg/L. Maximum depth: 25 ft. Surface area: 689.62 acres.
- Clarity
- 5.5 ft
- Typical in August
- 70°F
- Max depth
- 25 ft
- Area
- 690 acres
- Type
- Eutrophic
- Public access
- Yes
- Ice-out
- Apr 25
Next lake in St. Louis County
Ash Lake is a 690-acre productive, nutrient-rich eutrophic lake in St. Louis County, Minnesota with a maximum depth of 25 feet. Water quality is graded C based on 2 sampling years through 2025. The lake supports 9 documented fish species including black crappie, bluegill, and hybrid sunfish. Public access is available with 1 public boat landing. Compared to the 67 other monitored lakes in St. Louis County, Ash Lake ranks #60 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-17. Grade methodology: LakeGrade methodology.
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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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Murky, only visible to about 5.5 ft. Phosphorus level: 39 µg/L. Chlorophyll-a: 11.1 µg/L. Trophic State Index: 55.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.5 ft | Not graded |
| Phosphorus | 39 µg/L | Fair |
| Chlorophyll-a (Algae) | 11.1 µg/L | Fair |
| Trophic State Index (TSI) | 55 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Ash Lake
Compare lakeside cabins, hotels, and vacation rentals near Ash 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.
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Water Temperature
Ash Lake typically sits around 70°F at the surface in August. Summer average is about 68°F. Usually warmest in Aug (about 70°F) and coldest in May (about 57°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 63 field readings (2011–2025) via the EPA Water Quality Portal. See the full Ash Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 25 ft |
| Surface Area | 690 acres |
| Shoreline Length | 6 mi |
| Littoral Zone | 28% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Ash LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Ash Lake
Ice Season
Historical ice data from Minnesota DNR (7 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2012-03-26 (2012) | 2014-05-09 (2014) |
Most recent ice-out: 2020-04-28
EPA Impairment Status
Ash Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN69-0864-00 · Official waterbody report
County Ranking
Ranked #60 of 68 lakes in St. Louis County
Nearby Lakes in St. Louis County
Frequently asked questions about Ash Lake
What is the water quality grade for Ash Lake?
- Ash Lake in St. Louis County, Minnesota has a water quality grade of C (Fair). Water clarity: 5.5 ft visibility. Phosphorus: 39 µg/L. Chlorophyll-a (algae): 11.1 µg/L. Maximum depth: 25 ft. Surface area: 689.62 acres.
Is Ash Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Ash Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 11.1 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Ash Lake?
- Ash Lake typically sits around 70°F at the surface in August, from 63 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Ash Lake?
- Ash Lake has a maximum depth of 25 feet. The lake covers 689.62 acres.
What fish are in Ash Lake?
- Fish species found in Ash Lake include black crappie, bluegill, hybrid sunfish, northern pike, pumpkinseed, smallmouth bass, walleye, white sucker, yellow perch. Ash Lake is located in St. Louis County, Minnesota.
When does Ash Lake thaw?
- Ash Lake typically has ice-out around Apr 25.
Are there boat ramps on Ash Lake?
- Ash Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Ash Lake. Public access is listed as yes.
Explore Ash Lake across LakeGrade
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High nutrients, frequent algae, reduced clarity
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Where this data comes from
20 measurements from 1 monitoring station, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA20 samples · 2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
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)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate