Rumsey Slough Mouth Lake
Rumsey Slough Mouth Lake in Lake County, California has a water quality grade of C (Fair). Water clarity: 1.6 ft visibility. Chlorophyll-a (algae): 7.2 µg/L.
- Clarity
- 1.6 ft
- Type
- Eutrophic
Rumsey Slough Mouth Lake is a productive, nutrient-rich eutrophic lake in Lake County, California. Water quality is graded C based on 1 sampling years through 2026. Compared to the 35 other monitored lakes in Lake County, Rumsey Slough Mouth Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2026-04-30. Grade methodology: LakeGrade methodology.
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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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Very murky, less than 1.6 ft of visibility. Chlorophyll-a: 7.2 µg/L. Trophic State Index: 60.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 7.2 µg/L | Fair |
| Trophic State Index (TSI) | 60 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Rumsey Slough Mouth Lake
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Top-rated places to stay near Rumsey Slough Mouth Lake
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Fishing Rumsey Slough Mouth Lake
County Ranking
Ranked #3 of 36 lakes in Lake County
Nearby Lakes in Lake County
Frequently asked questions about Rumsey Slough Mouth Lake
Where is Rumsey Slough Mouth Lake?
- Rumsey Slough Mouth Lake is a lake in Lake County, California. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Rumsey Slough Mouth Lake?
- Rumsey Slough Mouth Lake in Lake County, California has a water quality grade of C (Fair). Water clarity: 1.6 ft visibility. Chlorophyll-a (algae): 7.2 µg/L.
Is Rumsey Slough Mouth Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Rumsey Slough Mouth Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 7.2 µg/L. Always check local health department advisories before swimming.
Explore Rumsey Slough Mouth Lake across LakeGrade
More California Lake Rankings
Other Grade C Lakes in California
Eutrophic Lakes in California
Where this data comes from
88 measurements from 1 monitoring station, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- Big Valley Band of Pomo Indians of the Big Valley Rancheria, California (Tribal)
CA_BVR88 samples · 2020–2026
Analytical methods
- Chlorophyll a
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.