Twenty-One Lake
Twenty-One Lake in Hubbard County, Minnesota has a water quality grade of A (Excellent). Water clarity: 17 ft visibility. Phosphorus: 10.5 µg/L. Chlorophyll-a (algae): 3.6 µg/L. Maximum depth: 51.5 ft. Surface area: 35.8 acres.
- Clarity
- 17 ft
- Typical in August
- 60°F
- Max depth
- 51.5 ft
- Area
- 36 acres
- Type
- Oligotrophic
- Public access
- Yes
Next lake in Hubbard County
Twenty-One Lake is a 36-acre cold, clear oligotrophic lake in Hubbard County, Minnesota with a maximum depth of 52 feet. Water quality is graded A based on 2 sampling years through 2023. The lake supports 6 documented fish species including bluegill, largemouth bass, and northern pike. Public access is available with 2 public boat landings. Compared to the 67 other monitored lakes in Hubbard County, Twenty-One Lake ranks #49 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-09-19. 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)
Crystal clear, you can see 17 ft down. Phosphorus level: 10.5 µg/L. Chlorophyll-a: 3.6 µg/L. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 17 ft | Not graded |
| Phosphorus | 10.5 µg/L | Good |
| Chlorophyll-a (Algae) | 3.6 µg/L | Good |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Twenty-One Lake
Compare lakeside cabins, hotels, and vacation rentals near Twenty-One Lake in Hubbard 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 Twenty-One Lake
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Water Temperature
Twenty-One Lake typically sits around 60°F at the surface in August. Summer average is about 62°F. Usually warmest in Jul (about 66°F) and coldest in May (about 54°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 53 field readings (2023–2023) via the EPA Water Quality Portal. See the full Twenty-One Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 51.5 ft |
| Surface Area | 36 acres |
| Shoreline Length | 1.2 mi |
| Littoral Zone | 64% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Twentyone LakePublic
- Bass LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Twenty-One Lake
DNR Fisheries Survey Summary
4 surveys on file from MN DNR Fisheries. Most recent: 2015-07-27 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 47.41 | 0.06 lb |
| Yellow Perch | 8.24 | 0.21 lb |
| Northern Pike | 7.43 | 1.97 lb |
| Pumpkinseed | 3.54 | 0.11 lb |
| Largemouth Bass | 1.19 | 0.73 lb |
| Rock Bass | 0.50 | 1.07 lb |
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.
Bluegill
Yellow Perch
Northern Pike
Pumpkinseed
From the 2015-07-27 survey
Lake Twenty-One is a small, 28 acre lake located within the Paul Bunyan State Forest in Hubbard County. There is a public access and day-use area with picnic sites on the north shore of the lake. There are DNR maintained primitive campground sites on the east shore and south shore between Lake Twenty-One and Nelson…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Twenty-One Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Twenty-OneFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Twenty-One (1315)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — Twenty-OnePublic Water Access Sites · MN DNR LakeFinder
County Ranking
Ranked #49 of 68 lakes in Hubbard County
Nearby Lakes in Hubbard County
Frequently asked questions about Twenty-One Lake
What is the water quality grade for Twenty-One Lake?
- Twenty-One Lake in Hubbard County, Minnesota has a water quality grade of A (Excellent). Water clarity: 17 ft visibility. Phosphorus: 10.5 µg/L. Chlorophyll-a (algae): 3.6 µg/L. Maximum depth: 51.5 ft. Surface area: 35.8 acres.
Is Twenty-One Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Twenty-One 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 Twenty-One Lake?
- Twenty-One Lake typically sits around 60°F at the surface in August, from 53 EPA Water Quality Portal field readings (2023–2023). That is a typical value for the month, not a live reading.
How deep is Twenty-One Lake?
- Twenty-One Lake has a maximum depth of 51.5 feet. The lake covers 35.8 acres.
What fish are in Twenty-One Lake?
- Fish species found in Twenty-One Lake include bluegill, largemouth bass, northern pike, pumpkinseed, rock bass, yellow perch. Twenty-One Lake is located in Hubbard County, Minnesota.
Are there boat ramps on Twenty-One Lake?
- Twenty-One Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Twentyone Lake, Bass Lake. Public access is listed as yes.
Explore Twenty-One Lake across LakeGrade
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Where this data comes from
62 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA62 samples · 2023
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory