Ross Lake
Snohomish County, WashingtonView 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
Ross Lake in Snohomish County, Washington is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 46 µg/L.
- Phosphorus
- 46 µg/L
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Watch Ross Lake’s letter
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Why Ross 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 Ross 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 WA Ecology and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Ross Lake is a lake in Snohomish County, Washington.
Source: EPA Water Quality Portal sampling records, WA Ecology, last sampled 2019-04-29. 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 Ross Lake
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Phosphorus 46 µg/L. TSI 59.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 46 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Fishing Ross Lake
Graded lakes near Ross Lake
Ross Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Snohomish County
Frequently asked questions about Ross Lake
Where is Ross Lake?
- Ross Lake is a lake in Snohomish County, Washington. 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 Ross Lake?
- Ross Lake in Snohomish County, Washington is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 46 µg/L.
Is Ross Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
Explore Ross Lake across LakeQuality
20.7 mi away · 120 ft
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Where this data comes from
17 measurements from 1 monitoring station, 2012–2019. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Tulalip Tribes (Tribal)
TRTUL_WQX17 samples · 2012–2019
Analytical methods
- Phosphorus, Total Ascorbic Acid Method
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.