Allen County, Ohio · Water Quality Report Card
Williams Reservoir
Williams Reservoir in Allen County, Ohio has a water quality grade of C (Fair). Phosphorus: 39.4 µg/L. Chlorophyll-a (algae): 19.8 µg/L.
- Type
- Eutrophic
Williams Reservoir is a productive, nutrient-rich eutrophic lake in Allen County, Ohio. Water quality is graded C based on 2 sampling years through 2024. Compared to the 6 other monitored lakes in Allen County, Williams Reservoir ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Ohio EPA, last sampled 2024-10-08. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swim with caution, moderate algae may be present
Water Quality Grade: C (Fair)
No clarity data. Phosphorus level: 39.4 µg/L. Chlorophyll-a: 19.8 µg/L. Trophic State Index: 59.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 39.4 µg/L | Fair |
| Chlorophyll-a (Algae) | 19.8 µg/L | Fair |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Williams Reservoir
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Fishing Williams Reservoir
Location
County Ranking
Ranked #4 of 7 lakes in Allen County
Nearby Lakes in Allen County
Explore Williams Reservoir across LakeGrade
More Ohio Lake Rankings
Other Grade C Lakes in Ohio
Eutrophic Lakes in Ohio
More records, surveys & data sources
Where this data comes from
74 measurements from 1 monitoring station, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Division of Surface water (Ohio)
21OHIO_WQX74 samples · 2024
Analytical methods
- Total Phosphorus After Block Digestion
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 2130 B ~ Nephelometric Method
Monitoring station identifiers (1)
Grade thresholds come from the U.S. EPA National Lakes Assessment 2022 Technical Support Document (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated.
Data Sources
Water quality data from the EPA Water Quality Portal
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2024-10-08
Monitoring stations: 1