Hannan Lake
Hannan Lake in Hennepin County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 4.3 ft visibility. Phosphorus: 52.5 µg/L. Chlorophyll-a (algae): 11 µg/L.
- Clarity
- 4.3 ft
- Typical in August
- 77°F
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- No
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Hannan Lake →
Next lake in Hennepin County
Hannan Lake is a productive, nutrient-rich eutrophic lake in Hennepin County, Minnesota. Water quality is graded D based on 2 sampling years through 2024. Overall water quality is declining over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 80 other monitored lakes in Hennepin County, Hannan Lake ranks #54 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-02. 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.
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)
Murky, only visible to about 4.3 ft. Phosphorus level: 52.5 µg/L. Chlorophyll-a: 11 µg/L. Trophic State Index: 57.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.3 ft | Not graded |
| Phosphorus | 52.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 11 µg/L | Fair |
| Trophic State Index (TSI) | 57 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Hannan Lake
Compare lakeside cabins, hotels, and vacation rentals near Hannan 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 Hannan Lake are listed below.
Top-rated places to stay near Hannan Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Hannan Lake typically sits around 77°F at the surface in August. Summer average is about 76°F. Usually warmest in Jul (about 81°F) and coldest in Oct (about 55°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 27 field readings (2010–2024) via the EPA Water Quality Portal. See the full Hannan Lake water temperature breakdown →
Fishing Hannan Lake
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.033 m/yr | 2 |
| Phosphorus | ↓ Declining | +9.5 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +3.13 µg/L/yr | 2 |
EPA Impairment Status
Hannan Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MN27-0053-00 · Official waterbody report · Matched by proximity (0.37 km)
County Ranking
Ranked #54 of 81 lakes in Hennepin County
Nearby Lakes With Higher Grades
Hannan 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 Hannan Lake
What is the water quality grade for Hannan Lake?
- Hannan Lake in Hennepin County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 4.3 ft visibility. Phosphorus: 52.5 µg/L. Chlorophyll-a (algae): 11 µg/L.
Is Hannan 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. Hannan Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 11 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Hannan Lake?
- Hannan Lake typically sits around 77°F at the surface in August, from 27 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
Explore Hannan Lake across LakeGrade
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Where this data comes from
20 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
MNPCA20 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