Conejos County, Colorado · Water Quality Report Card
Platoro Reservoir
Platoro Reservoir in Conejos County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 97.5 µg/L. Chlorophyll-a (algae): 5.8 µg/L.
- Mean depth
- ~70 ft est.
- Type
- Eutrophic
Platoro Reservoir is a productive, nutrient-rich eutrophic lake in Conejos County, Colorado with an estimated average depth of about 70 feet.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2023-06-21. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not rated for swimming — there is not enough monitoring data to judge this lake
Water Quality Grade: Not rated
No clarity data. Phosphorus level: 97.5 µg/L. Chlorophyll-a: 5.8 µg/L. Trophic State Index: 59.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 97.5 µg/L | |
| Chlorophyll-a (Algae) | 5.8 µg/L | |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~70 ft est. |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Colorado has not published bathymetry for Platoro Reservoir.
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Fishing Platoro Reservoir
Location
Nearby Lakes in Conejos County
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Eutrophic Lakes in Colorado
More records, surveys & data sources
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.
Where this data comes from
5 measurements from 2 monitoring stations, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Colorado Dept. of Public Health & Environment-WQCD
21COL001_WQX5 samples · 2023
Analytical methods
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Nitrogen in Water by Pyrolysis Detection
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2023-06-21
Monitoring stations: 2