Union Reservoir is a productive, nutrient-rich eutrophic lake in Weld County, Colorado. Water quality is graded F based on 1 sampling years through 2022. Compared to the 5 other monitored lakes in Weld County, Union Reservoir ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Colorado DNR, last sampled 2022-10-04. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 3.2 ft of visibility. Trophic State Index: 60.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.2 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 60 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Union Reservoir
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Fishing Union Reservoir
Location
County Ranking
Ranked #3 of 6 lakes in Weld County
Nearby Lakes in Weld County
Explore Union Reservoir across LakeGrade
More Colorado Lake Rankings
Other Grade F Lakes in Colorado
Eutrophic Lakes in Colorado
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: 2022-10-04
Monitoring stations: 2