N St Vrain Lake
Boulder 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
N St Vrain Lake in Boulder County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar.
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Stays near N St Vrain Lake
Compare lakeside cabins, hotels, and vacation rentals near N St Vrain Lake in Boulder County, Colorado — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
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Watch N St Vrain Lake’s letter
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Why N St Vrain 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 N St Vrain Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
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.
N St Vrain Lake is a lake in Boulder County, Colorado.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2024-10-29. 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 N St Vrain Lake
These readings exist but are not enough for an A–F grade — see why.
No clarity data.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples |
Fishing N St Vrain Lake
Graded lakes near N St Vrain Lake
N St Vrain Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Boulder County
Frequently asked questions about N St Vrain Lake
Where is N St Vrain Lake?
- N St Vrain Lake is a lake in Boulder 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 N St Vrain Lake?
- N St Vrain Lake in Boulder County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar.
Is N St Vrain Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
Explore N St Vrain Lake across LakeQuality
Planning a trip around Rocky Mountain?
N St Vrain Lake is about 23 miles from Rocky Mountain National Park. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Rocky Mountain →More Colorado Lake Rankings
Other Lakes in Colorado
Where this data comes from
4 measurements from 1 monitoring station, 2023–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Colorado River Watch (Volunteer)
CORIVWCH_WQX4 samples · 2023–2024
Analytical methods
- Phosphorus by Colorimetry
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.