Cox Lake
Calhoun County, TexasView 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.
- 40 ft max depth
- Public access
- Limited data
Cox Lake in Calhoun County, Texas is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 0.7 ft visibility. Phosphorus: 303 µg/L. Chlorophyll-a (algae): 15.8 µg/L.
- Clarity
- 0.7 ft
- Max depth
- ~40 ft est.
- Phosphorus
- 303 µg/L
- Chlorophyll-a
- 15.8 µg/L
- Trend
- → Stable
- Public access
- Yes
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Watch Cox Lake’s letter
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Why Cox Lake 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 Cox Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).
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 TCEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Cox Lake is a lake in Calhoun County, Texas with an estimated average depth of about 40 feet. Phosphorus level is declining over recent sampling years. Limited fish-species data available. Public access is available.
Source: EPA Water Quality Portal sampling records, TCEQ, last sampled 2025-11-20. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Cox Lake
These readings exist but are not enough for an A–F grade — see why.
Very murky, less than 0.7 ft of visibility. Phosphorus 303 µg/L. Chlorophyll-a 15.8 µg/L. TSI 76.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.7 ft | Not graded |
| Phosphorus | 303 µg/L | Not graded |
| Chlorophyll-a (Algae) | 15.8 µg/L | Not graded |
| Trophic State Index (TSI) | 76 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~40 ft est. |
| Average Depth | ~6 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Texas has not published bathymetry for Cox Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Cox Lake
Water Quality Trend: → Stable
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↓ Declining | +17 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -6.75 µg/L/yr | 2 |
Graded lakes near Cox Lake
Cox Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Calhoun County
Frequently asked questions about Cox Lake
Where is Cox Lake?
- Cox Lake is a lake in Calhoun County, Texas. 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 Cox Lake?
- Cox Lake in Calhoun County, Texas is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 0.7 ft visibility. Phosphorus: 303 µg/L. Chlorophyll-a (algae): 15.8 µg/L.
Is Cox Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
How deep is Cox Lake?
- No published bathymetric survey covers Cox Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 40 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Cox Lake across LakeQuality
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Where this data comes from
31 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Texas Commission on Environmental Quality
TCEQMAIN31 samples · 2020–2025
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
Lake size & watershed from HydroLAKES (HydroSHEDS)