Tappan Lake @ Cadiz Public Water Supply Intake
Harrison County, OhioView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- Impaired · Algal growth
- Limited data
Tappan Lake @ Cadiz Public Water Supply Intake in Harrison County, Ohio is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 66.1 µg/L. Chlorophyll-a (algae): 72.1 µg/L.
- Phosphorus
- 66.1 µg/L
- Chlorophyll-a
- 72.1 µg/L
- Trend
- ↓ Declining
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Watch Tappan Lake @ Cadiz Public Water Supply Intake’s letter
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Why Tappan Lake @ Cadiz Public Water Supply Intake has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Tappan Lake @ Cadiz Public Water Supply Intake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded phosphorus and algae (chlorophyll-a), but not water clarity.
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by Ohio EPA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
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 Safety
Not ratedLimited data
The letter is 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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Water quality measurements for Tappan Lake @ Cadiz Public Water Supply Intake
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Phosphorus 66.1 µg/L. Chlorophyll-a 72.1 µg/L. TSI 69.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 66.1 µg/L | Not graded |
| Chlorophyll-a (Algae) | 72.1 µg/L | Not graded |
| 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)
Graded lakes near Tappan Lake @ Cadiz Public Water Supply Intake
Tappan Lake @ Cadiz Public Water Supply Intake has no grade, but these lakes within a short drive do.
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. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Tappan Lake @ Cadiz Public Water Supply Intake?
- Tappan Lake @ Cadiz Public Water Supply Intake in Harrison County, Ohio is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 66.1 µg/L. Chlorophyll-a (algae): 72.1 µg/L.
Is Tappan Lake @ Cadiz Public Water Supply Intake safe to swim in?
- The letter is 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)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database