Little Eldorado Lake
San Juan County, ColoradoView mapDirections
Clarity, phosphorus, and algae sit in the clean band for this region.
↓ down from A at the last regrade
- Oligotrophic
- #1 of 1 in the county
- Limited data
Little Eldorado Lake in San Juan County, Colorado has a water quality grade of B (Good). Phosphorus: 4 µg/L.
- Type
- Oligotrophic
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Watch Little Eldorado Lake’s letter
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Little Eldorado Lake is a cold, clear oligotrophic lake in San Juan County, Colorado. Water quality is graded B based on 1 sampling years through 2020.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2020-09-21. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The B is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: B (Good)
No clarity data. Phosphorus 4 µg/L. TSI 24. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 4 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 24 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Fishing Little Eldorado Lake
County Ranking
Ranked #1 of 1 lakes in San Juan County
Nearby Lakes in San Juan County
Frequently asked questions about Little Eldorado Lake
Where is Little Eldorado Lake?
- Little Eldorado Lake is a lake in San Juan County, Colorado. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Little Eldorado Lake?
- Little Eldorado Lake in San Juan County, Colorado has a water quality grade of B (Good). Phosphorus: 4 µg/L.
Is Little Eldorado Lake safe to swim in?
- The B is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Little Eldorado Lake across LakeQuality
3 documented falls within 23.6 mi, nearest Bridal Veil Falls
22.3 mi away · recorded at 156°F
Species activity outlook by water temperature and season
Where to stay at Colorado's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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Where this data comes from
3 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-CO3 samples · 2020
Analytical methods
- P, wu, WCA, persulfate CF color
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.