Tappan Lake @ Cadiz Public Water Supply Intake
Harrison County, OhioView mapDirections
Ohio EPA publishes the water-quality measurements for Tappan Lake @ Cadiz Public Water Supply Intake. Here is what has been measured.
- Impaired · Algal growth
- Limited data
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Answers come straight from the public measurements and survey records on this page.
Tappan Lake @ Cadiz Public Water Supply Intake in Harrison County, Ohio has water-quality measurements published by Ohio EPA, shown here as reported. Phosphorus: 66.1 µg/L. Chlorophyll-a (algae): 72.1 µg/L.
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Tappan Lake @ Cadiz Public Water Supply Intake is a lake in Harrison County, Ohio. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, Ohio EPA, last sampled 2022-08-22. Grade methodology: LakeQuality methodology.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Tappan Lake @ Cadiz Public Water Supply Intake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
Whether Tappan Lake @ Cadiz Public Water Supply Intake 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.
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Water quality measurements for Tappan Lake @ Cadiz Public Water Supply Intake
These are the measurements Ohio EPA publishes for Tappan Lake @ Cadiz Public Water Supply Intake, 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 66.1 µg/L. Chlorophyll-a 72.1 µg/L. TSI 69.
| Metric | Value | EPA condition class |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 66.1 µg/L | Measured, not scored |
| Chlorophyll-a (Algae) | 72.1 µg/L | Measured, not scored |
| Trophic State Index (TSI) | 69 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Fishing Tappan Lake @ Cadiz Public Water Supply Intake
Water Quality Trend: ↓ Declining
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -2.54 m/yr | 2 |
| Phosphorus | → Stable | +1.35 µg/L/yr | 2 |
EPA Impairment Status
Tappan Lake @ Cadiz Public Water Supply Intake 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 OH050400011503 · Official waterbody report · Matched by proximity (2.06 km)
Nearby Lakes in Harrison County
Frequently asked questions about Tappan Lake @ Cadiz Public Water Supply Intake
Where is Tappan Lake @ Cadiz Public Water Supply Intake?
- Tappan Lake @ Cadiz Public Water Supply Intake is a lake in Harrison County, Ohio. Its water-quality measurements are published by Ohio EPA and shown on this page as reported.
What is the water quality of Tappan Lake @ Cadiz Public Water Supply Intake?
- Tappan Lake @ Cadiz Public Water Supply Intake in Harrison County, Ohio has water-quality measurements published by Ohio EPA, shown here as reported. Phosphorus: 66.1 µg/L. Chlorophyll-a (algae): 72.1 µg/L.
Is Tappan Lake @ Cadiz Public Water Supply Intake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Tappan Lake @ Cadiz Public Water Supply Intake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
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Where this data comes from
5 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Division of Surface water (Ohio)
21OHIO_WQX5 samples · 2022
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