Faherty Lake
Faherty Lake in Cass County, Minnesota has a water quality grade of C (Fair). Water clarity: 6.2 ft visibility. Phosphorus: 26.5 µg/L. Chlorophyll-a (algae): 10.7 µg/L.
- Clarity
- 6.2 ft
- Typical in August
- 68°F
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Cass County
Faherty Lake is a productive, nutrient-rich eutrophic lake in Cass County, Minnesota. Water quality is graded C based on 2 sampling years through 2021. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 103 other monitored lakes in Cass County, Faherty Lake ranks #92 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2021-10-20. Grade methodology: LakeGrade methodology.
Watch Faherty 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 6.2 ft. Phosphorus level: 26.5 µg/L. Chlorophyll-a: 10.7 µg/L. Trophic State Index: 52.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.2 ft | Not graded |
| Phosphorus | 26.5 µg/L | Fair |
| Chlorophyll-a (Algae) | 10.7 µg/L | Fair |
| Trophic State Index (TSI) | 52 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Faherty Lake
Compare lakeside cabins, hotels, and vacation rentals near Faherty Lake in Cass 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
Faherty Lake typically sits around 68°F at the surface in August. Summer average is about 65°F. Usually warmest in Aug (about 68°F) and coldest in May (about 52°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 328 field readings (2021–2021) via the EPA Water Quality Portal. See the full Faherty Lake water temperature breakdown →
Recreation & Access
- Thirteen LakePublic
Fishing Faherty Lake
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Faherty Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Aquatic Plant Report — Faherty (1633)Aquatic Plant Report · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.619 m/yr | 3 |
| Phosphorus | ↑ Improving | -3.96 µg/L/yr | 3 |
| Chlorophyll-a | ↑ Improving | -1.32 µg/L/yr | 3 |
Reservoir Info (USACE NID)
Faherty Lake is a man-made reservoir impounded by the Highland Creek (completed 1970), built primarily for other on the Highland Creek; earth-type dam, 11 ft tall and 320 ft long.
- Normal storage
- 62 ac-ft
- Max storage
- 232 ac-ft
- Drainage area
- 0.6 sq mi
- Hazard class
- Low
- Owner
- USDA FS
Source: USACE National Inventory of Dams, NID ID MN00648 · Operator website · Matched by proximity (0.71 km)
County Ranking
Ranked #92 of 104 lakes in Cass County
Nearby Lakes With Higher Grades
Faherty Lake holds Grade C. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Cass County
Frequently asked questions about Faherty Lake
What is the water quality grade for Faherty Lake?
- Faherty Lake in Cass County, Minnesota has a water quality grade of C (Fair). Water clarity: 6.2 ft visibility. Phosphorus: 26.5 µg/L. Chlorophyll-a (algae): 10.7 µg/L.
Is Faherty Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Faherty Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 10.7 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Faherty Lake?
- Faherty Lake typically sits around 68°F at the surface in August, from 328 EPA Water Quality Portal field readings (2021–2021). That is a typical value for the month, not a live reading.
Are there boat ramps on Faherty Lake?
- Faherty Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Thirteen Lake. Public access is listed as yes.
Explore Faherty Lake across LakeGrade
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High nutrients, frequent algae, reduced clarity
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Where this data comes from
67 measurements from 1 monitoring station, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Leech Lake Band of Ojibwe
LEECHLAK_WQX67 samples · 2021
Analytical methods
- 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
Named boat-access points from the USGS National Boat Ramps inventory