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LakeQuality
C

Faherty Lake

Cass County, MinnesotaEutrophic

The LakeGrade rubric puts Faherty Lake at a C: clarity at 6.2 ft, 27 µg/L of phosphorus, and a TSI of 52 signal an intermediate trophic state. Secchi readings are the weakest of the three parameters, suggesting suspended sediment or algal biomass dominates the optical signal.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Faherty Lake ranks 126 of 133 in Cass County — at the lower end of the locally monitored distribution.

No invasive species are currently listed at Faherty Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Faherty Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Faherty Lake — most use is by shoreline residents and their guests. The grade is supported by multiple sampling years from Minnesota PCA volunteers and partner agencies, giving the letter a reasonably stable foundation.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2021-10-20. Grade methodology: LakeGrade methodology.

Swimming Safety

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.

MetricValueGrade
Water Clarity (Secchi Depth)6.2 ftD
Phosphorus26.5 µg/LB
Chlorophyll-a (Algae)10.7 µg/LC
Trophic State Index (TSI)52Eutrophic

High nutrients, frequent algae, reduced clarity

Water Quality Trend: Improving

Based on 3 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.619 m/yr3
Phosphorus Improving-3.61 µg/L/yr3
Chlorophyll-a Improving-3.25 µg/L/yr2

Location

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County Ranking

Ranked #126 of 133 lakes in Cass County

Nearby Lakes in Cass County

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Faherty Lake. 1 report on file.

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2021-10-20

Monitoring stations: 1