Upper Grizzly Lake
La Plata County, ColoradoView 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.
- Limited data
Upper Grizzly Lake in La Plata County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 6.5 µg/L.
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Watch Upper Grizzly Lake’s letter
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Why Upper Grizzly 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 Upper Grizzly Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded phosphorus, but not water clarity 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 CDPHE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Upper Grizzly Lake is a lake in La Plata County, Colorado.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2020-09-23. 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 Upper Grizzly Lake
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Phosphorus 6.5 µg/L. TSI 31.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 6.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 31 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Fishing Upper Grizzly Lake
Graded lakes near Upper Grizzly Lake
Upper Grizzly Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in La Plata County
Frequently asked questions about Upper Grizzly Lake
Where is Upper Grizzly Lake?
- Upper Grizzly Lake is a lake in La Plata County, Colorado. 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 Upper Grizzly Lake?
- Upper Grizzly Lake in La Plata County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 6.5 µg/L.
Is Upper Grizzly Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
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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)
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.