Penn Lake
Penn Lake in Hennepin County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 2 ft visibility. Phosphorus: 55 µg/L. Chlorophyll-a (algae): 14.5 µg/L. Maximum depth: 7 ft. Surface area: 43.7 acres.
- Clarity
- 2 ft
- Typical in August
- 81°F
- Max depth
- 7 ft
- Area
- 44 acres
- Type
- Eutrophic
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Penn Lake →
Next lake in Hennepin County
Penn Lake is a 44-acre productive, nutrient-rich eutrophic lake in Hennepin County, Minnesota with a maximum depth of 7 feet. Water quality is graded D based on 2 sampling years through 2024. The lake supports 8 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 1 public boat landing. Compared to the 80 other monitored lakes in Hennepin County, Penn Lake ranks #53 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-14. Grade methodology: LakeGrade methodology.
Watch Penn 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.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 2 ft of visibility. Phosphorus level: 55 µg/L. Chlorophyll-a: 14.5 µg/L. Trophic State Index: 62.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | Not graded |
| Phosphorus | 55 µg/L | Poor |
| Chlorophyll-a (Algae) | 14.5 µg/L | Fair |
| Trophic State Index (TSI) | 62 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Penn Lake
Compare lakeside cabins, hotels, and vacation rentals near Penn Lake in Hennepin 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Penn Lake are listed below.
Top-rated places to stay near Penn 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
Penn Lake typically sits around 81°F at the surface in August. Summer average is about 80°F. Usually warmest in Jul (about 83°F) and coldest in Oct (about 51°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 42 field readings (2010–2024) via the EPA Water Quality Portal. See the full Penn Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 7 ft |
| Surface Area | 44 acres |
| Shoreline Length | 2.3 mi |
| Littoral Zone | 98% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Penn LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Penn Lake
EPA Impairment Status
Penn 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 MN27-0004-00 · Official waterbody report
County Ranking
Ranked #53 of 81 lakes in Hennepin County
Nearby Lakes With Higher Grades
Penn Lake holds Grade D. 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 Hennepin County
Frequently asked questions about Penn Lake
What is the water quality grade for Penn Lake?
- Penn Lake in Hennepin County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 2 ft visibility. Phosphorus: 55 µg/L. Chlorophyll-a (algae): 14.5 µg/L. Maximum depth: 7 ft. Surface area: 43.7 acres.
Is Penn Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Penn Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 14.5 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Penn Lake?
- Penn Lake typically sits around 81°F at the surface in August, from 42 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
How deep is Penn Lake?
- Penn Lake has a maximum depth of 7 feet. The lake covers 43.7 acres.
What fish are in Penn Lake?
- Fish species found in Penn Lake include bigmouth buffalo, black bullhead, black crappie, bluegill, common carp, green sunfish, hybrid sunfish, yellow perch. Penn Lake is located in Hennepin County, Minnesota.
Are there boat ramps on Penn Lake?
- Penn Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Penn Lake. Public access is listed as yes.
Explore Penn Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Hennepin County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Crow River Watershed, ranked by water quality
High nutrients, frequent algae, reduced clarity
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Penn Lake
Other Grade D Lakes in Minnesota
Eutrophic Lakes in Minnesota
Where this data comes from
52 measurements from 1 monitoring station, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA52 samples · 2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Analysis of Chlorophyll in Periphyton and Plankton
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