Blackwell Lake
Blackwell Lake in Douglas County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.5 ft visibility. Phosphorus: 14.5 µg/L. Chlorophyll-a (algae): 5.8 µg/L. Maximum depth: 42 ft. Surface area: 307.37 acres.
- Clarity
- 11.5 ft
- Typical in August
- 74°F
- Max depth
- 42 ft
- Area
- 307 acres
- Type
- Mesotrophic
- Public access
- Yes
Next lake in Douglas County
Blackwell Lake is a 307-acre mesotrophic lake in Douglas County, Minnesota with a maximum depth of 42 feet (10-foot average). Water quality is graded A based on 2 sampling years through 2022. The lake supports 12 documented fish species including black crappie, bluegill, and brown bullhead. Public access is available with 2 public boat landings. Compared to the 36 other monitored lakes in Douglas County, Blackwell Lake ranks #25 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-09-14. 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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 11.5 ft. Phosphorus level: 14.5 µg/L. Chlorophyll-a: 5.8 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11.5 ft | Not graded |
| Phosphorus | 14.5 µg/L | Good |
| Chlorophyll-a (Algae) | 5.8 µg/L | Good |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Blackwell Lake
Compare lakeside cabins, hotels, and vacation rentals near Blackwell Lake in Douglas 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
Blackwell Lake typically sits around 74°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 74°F) and coldest in Sep (about 71°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 10 field readings (2010–2022) via the EPA Water Quality Portal. See the full Blackwell Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 42 ft |
| Average Depth | 10 ft |
| Surface Area | 307 acres |
| Shoreline Length | 5.2 mi |
| Littoral Zone | 66% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Blackwell Lake (South)Public
- Grants LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Blackwell Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Fisheries Survey Summary
12 surveys on file from MN DNR Fisheries. Most recent: 2022-07-11 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Largemouth Bass | 33.54 | 0.92 lb |
| Bluegill | 20.30 | 0.16 lb |
| Bluntnose Minnow | 11.82 | — |
| Green Sunfish | 10.03 | 0.24 lb |
| Black Crappie | 7.76 | 0.29 lb |
| BNS | 6.50 | — |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Largemouth Bass
Bluegill
Green Sunfish
Black Crappie
From the 2022-07-11 survey
A trap net survey was conducted on Blackwell Lake on July 11-12, 2022 by Index of Biological Integrity (IBI) Program Staff. Nine trap nets were set along the shoreline in locations that encompassed multiple habitat types. Bluegill comprised a majority of the trap net catch by number. The number of Bluegill sampled per…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Blackwell Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — BlackwellFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Blackwell (1079)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — BlackwellPublic Water Access Sites · MN DNR LakeFinder
EPA Impairment Status
Blackwell 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 MN21-0157-00 · Official waterbody report · Matched by proximity (1.91 km)
County Ranking
Ranked #25 of 37 lakes in Douglas County
Nearby Lakes in Douglas County
Frequently asked questions about Blackwell Lake
What is the water quality grade for Blackwell Lake?
- Blackwell Lake in Douglas County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.5 ft visibility. Phosphorus: 14.5 µg/L. Chlorophyll-a (algae): 5.8 µg/L. Maximum depth: 42 ft. Surface area: 307.37 acres.
Is Blackwell Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Blackwell Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 5.8 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Blackwell Lake?
- Blackwell Lake typically sits around 74°F at the surface in August, from 10 EPA Water Quality Portal field readings (2010–2022). That is a typical value for the month, not a live reading.
How deep is Blackwell Lake?
- Blackwell Lake has a maximum depth of 42 feet and an average depth of 10 feet. The lake covers 307.37 acres.
What fish are in Blackwell Lake?
- Fish species found in Blackwell Lake include black crappie, bluegill, brown bullhead, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white sucker, yellow bullhead, yellow perch. Blackwell Lake is located in Douglas County, Minnesota.
Are there boat ramps on Blackwell Lake?
- Blackwell Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Blackwell Lake (South), Grants Lake. Public access is listed as yes.
Explore Blackwell Lake across LakeGrade
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Moderate nutrients, good water quality
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Where this data comes from
14 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA14 samples · 2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent 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