Horsetail Lake is a productive, nutrient-rich eutrophic lake in Cook County, Illinois. Water quality is graded D based on 1 sampling years through 2022. Compared to the 67 other monitored lakes in Cook County, Horsetail Lake ranks #22 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois DNR, last sampled 2022-03-24. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Murky, only visible to about 5 ft. Trophic State Index: 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Horsetail Lake
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Top-rated places to stay near Horsetail Lake
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Fishing Horsetail Lake
Water Temperature
Horsetail Lake averages about 81°F at the surface in summer, usually warmest in Jul (about 84°F) and coldest in Oct (about 58°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 42 field readings (2010–2022) via the EPA Water Quality Portal.
Location
County Ranking
Ranked #22 of 68 lakes in Cook County
Nearby Lakes in Cook County
Explore Horsetail Lake across LakeGrade
More Illinois Lake Rankings
Other Grade D Lakes in Illinois
Eutrophic Lakes in Illinois
More records, surveys & data sources
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2022-03-24
Monitoring stations: 1