Allen County, Ohio · Water Quality Report Card
Ottawa R Lake
Ottawa R Lake in Allen County, Ohio has a water quality grade of C (Fair). Phosphorus: 207 µg/L. Chlorophyll-a (algae): 2.1 µg/L.
- Type
- Mesotrophic
Ottawa R Lake is a mesotrophic 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, Ottawa R Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Ohio EPA, last sampled 2024-09-12. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
No clarity data. Phosphorus level: 207 µg/L. Chlorophyll-a: 2.1 µg/L. Trophic State Index: 60.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 207 µg/L | Poor |
| Chlorophyll-a (Algae) | 2.1 µg/L | Good |
| Trophic State Index (TSI) | 60 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Ottawa R Lake
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Fishing Ottawa R Lake
Location
County Ranking
Ranked #2 of 7 lakes in Allen County
Nearby Lakes in Allen County
Explore Ottawa R Lake across LakeGrade
More Ohio Lake Rankings
Other Grade C Lakes in Ohio
Mesotrophic Lakes in Ohio
More records, surveys & data sources
EPA Impairment Status
Ottawa R Lake 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 OH041000070402 · Official waterbody report · Matched by proximity (2.14 km)
Where this data comes from
14 measurements from 2 monitoring stations, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Division of Surface water (Ohio)
21OHIO_WQX14 samples · 2024
Analytical methods
- Total Phosphorus After Block Digestion
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (2)
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
Impairment status from EPA ATTAINS 303(d) database
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2024-09-12
Monitoring stations: 2