Big Eldorado Lake
San Juan County, ColoradoView mapDirections
Colorado WQCD publishes the water-quality measurements for Big Eldorado Lake. Here is what has been measured.
- Limited data
Ask about Big Eldorado Lake
Answers come straight from the public measurements and survey records on this page.
Big Eldorado Lake in San Juan County, Colorado has water-quality measurements published by Colorado WQCD, shown here as reported. Phosphorus: 3.5 µg/L.
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Big Eldorado Lake is a lake in San Juan County, Colorado.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2020-09-21. Grade methodology: LakeQuality methodology.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Big Eldorado Lake is safe to swim in today is a call for the Water Quality Control Division of the Colorado Department of Public Health and Environment and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Big Eldorado Lake
These are the measurements Colorado WQCD publishes for Big Eldorado Lake, 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 3.5 µg/L. TSI 22.
| Metric | Value | EPA condition class |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 3.5 µg/L | Measured, not scored |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 22 | Oligotrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Fishing Big Eldorado Lake
Nearby Lakes in San Juan County
Frequently asked questions about Big Eldorado Lake
Where is Big Eldorado Lake?
- Big Eldorado Lake is a lake in San Juan County, Colorado. Its water-quality measurements are published by Colorado WQCD and shown on this page as reported.
What is the water quality of Big Eldorado Lake?
- Big Eldorado Lake in San Juan County, Colorado has water-quality measurements published by Colorado WQCD, shown here as reported. Phosphorus: 3.5 µg/L.
Is Big Eldorado Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Big Eldorado Lake across LakeQuality
3 documented falls within 23.5 mi, nearest Bridal Veil Falls
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Where this data comes from
2 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Colorado Water Science Center
USGS-CO2 samples · 2020
Analytical methods
- P, wu, WCA, persulfate CF color
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.