Dark Lake
Dark Lake in Koochiching County, Minnesota has a water quality grade of C (Fair). Water clarity: 6.4 ft visibility. Phosphorus: 139.5 µg/L. Chlorophyll-a (algae): 5.8 µg/L. Maximum depth: 50 ft. Surface area: 119.61 acres.
- Clarity
- 6.4 ft
- Typical in August
- 57°F
- Max depth
- 50 ft
- Area
- 120 acres
- Type
- Eutrophic
- Public access
- Yes
Next lake in Koochiching County
Dark Lake is a 120-acre productive, nutrient-rich eutrophic lake in Koochiching County, Minnesota with a maximum depth of 50 feet. Water quality is graded C based on 2 sampling years through 2025. The lake supports 10 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 2 public boat landings. Compared to the 2 other monitored lakes in Koochiching County, Dark Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-02. Grade methodology: LakeGrade methodology.
Watch Dark Lake water quality
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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 6.4 ft. Phosphorus level: 139.5 µg/L. Chlorophyll-a: 5.8 µg/L. Trophic State Index: 58.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.4 ft | Not graded |
| Phosphorus | 139.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 5.8 µg/L | Good |
| Trophic State Index (TSI) | 58 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Dark Lake
Compare lakeside cabins, hotels, and vacation rentals near Dark Lake in Koochiching 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 Dark Lake
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Water Temperature
Dark Lake typically sits around 57°F at the surface in August. Summer average is about 55°F. Usually warmest in Aug (about 57°F) and coldest in Jun (about 51°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 48 field readings (2025–2025) via the EPA Water Quality Portal. See the full Dark Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 50 ft |
| Surface Area | 120 acres |
| Shoreline Length | 3.1 mi |
| Littoral Zone | 59% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Dark LakePublic
- Clear Lake, LodgePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Dark Lake
Reservoir Info (USACE NID)
Dark Lake is a man-made reservoir impounded by the Clear Dark Little Lakes (completed 1958), built primarily for other on the Lost River-TR; gravity-type dam, 7 ft tall and 12 ft long.
- Surface area
- 78 ac
- Normal storage
- 2,370 ac-ft
- Max storage
- 2,904 ac-ft
- Drainage area
- 3.1 sq mi
- Hazard class
- Low
- Owner
- MNDNR
Source: USACE National Inventory of Dams, NID ID MN00091 · Operator website · Matched by proximity (0.76 km)
EPA Impairment Status
Dark 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 MN36-0014-00 · Official waterbody report
County Ranking
Ranked #3 of 3 lakes in Koochiching County
Nearby Lakes With Higher Grades
Dark Lake holds Grade C. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Koochiching County
Frequently asked questions about Dark Lake
What is the water quality grade for Dark Lake?
- Dark Lake in Koochiching County, Minnesota has a water quality grade of C (Fair). Water clarity: 6.4 ft visibility. Phosphorus: 139.5 µg/L. Chlorophyll-a (algae): 5.8 µg/L. Maximum depth: 50 ft. Surface area: 119.61 acres.
Is Dark Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Dark Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 5.8 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Dark Lake?
- Dark Lake typically sits around 57°F at the surface in August, from 48 EPA Water Quality Portal field readings (2025–2025). That is a typical value for the month, not a live reading.
How deep is Dark Lake?
- Dark Lake has a maximum depth of 50 feet. The lake covers 119.61 acres.
What fish are in Dark Lake?
- Fish species found in Dark Lake include black bullhead, black crappie, bluegill, brown bullhead, largemouth bass, northern pike, rock bass, walleye, white sucker, yellow perch. Dark Lake is located in Koochiching County, Minnesota.
Are there boat ramps on Dark Lake?
- Dark Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Dark Lake, Clear Lake, Lodge. Public access is listed as yes.
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Where this data comes from
16 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
MNPCA16 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