Ferguson Reservoir
Allen County, OhioView mapDirections
Ohio EPA publishes the water-quality measurements for Ferguson Reservoir. Here is what has been measured.
- Eutrophic
- Impaired · Algal growth
- Limited data
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Answers come straight from the public measurements and survey records on this page.
Ferguson Reservoir in Allen County, Ohio has water-quality measurements published by Ohio EPA, shown here as reported. Phosphorus: 131 µg/L. Chlorophyll-a (algae): 13.4 µg/L.
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Ferguson Reservoir is a productive, nutrient-rich eutrophic lake in Allen County, Ohio. Compared to the 6 other monitored lakes in Allen County, Ferguson Reservoir ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Ohio EPA, last sampled 2024-09-18. Grade methodology: LakeQuality methodology.
Swimming conditions
Readings onlyBacteria advisory
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Ferguson Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, ammonia, cause unknown, habitat alterations, hydrologic alteration, nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pathogens (E. coli, fecal), pCBs, sediment / turbidity. Check local advisories before you swim.
Whether Ferguson Reservoir is safe to swim in today is a call for the Ohio Environmental Protection Agency and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Ferguson Reservoir
These are the measurements Ohio EPA publishes for Ferguson Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Phosphorus 131 µg/L. Chlorophyll-a 13.4 µg/L. TSI 65.
| Metric | Value | EPA condition class |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 131 µg/L | Poor |
| Chlorophyll-a (Algae) | 13.4 µg/L | Good |
| Trophic State Index (TSI) | 65 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Fishing Ferguson Reservoir
EPA Impairment Status
Ferguson Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit OH041000070306 · Official waterbody report · Matched by proximity (0.16 km)
Nearby Lakes in Allen County
Frequently asked questions about Ferguson Reservoir
Where is Ferguson Reservoir?
- Ferguson Reservoir is a lake in Allen County, Ohio. Its water-quality measurements are published by Ohio EPA and shown on this page as reported.
What is the water quality of Ferguson Reservoir?
- Ferguson Reservoir in Allen County, Ohio has water-quality measurements published by Ohio EPA, shown here as reported. Phosphorus: 131 µg/L. Chlorophyll-a (algae): 13.4 µg/L.
Is Ferguson Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Ferguson Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, ammonia, cause unknown, habitat alterations, hydrologic alteration, nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pathogens (E. coli, fecal), pCBs, sediment / turbidity. Check local advisories before you swim.
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Where this data comes from
51 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_WQX51 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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database