Upper Nwl Packtrail Pothole Lake
Rio Blanco 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 Nwl Packtrail Pothole Lake in Rio Blanco County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 56 µg/L.
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Why Upper Nwl Packtrail Pothole 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 Nwl Packtrail Pothole 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 Nwl Packtrail Pothole Lake is a lake in Rio Blanco County, Colorado.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2020-09-03. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Upper Nwl Packtrail Pothole Lake is listed impaired under Clean Water Act §303(d) (IR 5) for oxygen depletion (low DO). Check local advisories before you swim.
Water quality measurements for Upper Nwl Packtrail Pothole Lake
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Phosphorus 56 µg/L. TSI 62.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 56 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 62 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Fishing Upper Nwl Packtrail Pothole Lake
EPA Impairment Status
Upper Nwl Packtrail Pothole Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit COLCWH24_C · Official waterbody report · Matched by proximity (0.43 km)
Graded lakes near Upper Nwl Packtrail Pothole Lake
Upper Nwl Packtrail Pothole Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Rio Blanco County
Frequently asked questions about Upper Nwl Packtrail Pothole Lake
Where is Upper Nwl Packtrail Pothole Lake?
- Upper Nwl Packtrail Pothole Lake is a lake in Rio Blanco 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 Nwl Packtrail Pothole Lake?
- Upper Nwl Packtrail Pothole Lake in Rio Blanco County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 56 µg/L.
Is Upper Nwl Packtrail Pothole Lake safe to swim in?
- The letter is not a swimming clearance. Upper Nwl Packtrail Pothole Lake is listed impaired under Clean Water Act §303(d) (IR 5) for oxygen depletion (low DO). Check local advisories before you swim.
Explore Upper Nwl Packtrail Pothole Lake across LakeQuality
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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.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database