Rumsey Slough by the Old Bridge Lake
Rumsey Slough by the Old Bridge Lake in Lake County, California has a water quality grade of A (Excellent). Chlorophyll-a (algae): 4.6 µg/L.
- Type
- Mesotrophic
Rumsey Slough by the Old Bridge Lake is a mesotrophic lake in Lake County, California. Water quality is graded A based on 1 sampling years through 2026. Compared to the 35 other monitored lakes in Lake County, Rumsey Slough by the Old Bridge Lake ranks #1 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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
No clarity data. Chlorophyll-a: 4.6 µg/L. Trophic State Index: 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 4.6 µg/L | Good |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Rumsey Slough by the Old Bridge Lake
Compare lakeside cabins, hotels, and vacation rentals near Rumsey Slough by the Old Bridge Lake in Lake County, California — 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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Fishing Rumsey Slough by the Old Bridge Lake
County Ranking
Ranked #1 of 36 lakes in Lake County
Nearby Lakes in Lake County
Frequently asked questions about Rumsey Slough by the Old Bridge Lake
Where is Rumsey Slough by the Old Bridge Lake?
- Rumsey Slough by the Old Bridge Lake is a lake in Lake County, California. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Rumsey Slough by the Old Bridge Lake?
- Rumsey Slough by the Old Bridge Lake in Lake County, California has a water quality grade of A (Excellent). Chlorophyll-a (algae): 4.6 µg/L.
Is Rumsey Slough by the Old Bridge Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Rumsey Slough by the Old Bridge Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 4.6 µg/L. Always check local health department advisories before swimming.
Explore Rumsey Slough by the Old Bridge Lake across LakeGrade
More California Lake Rankings
Other Grade A Lakes in California
Mesotrophic Lakes in California
Where this data comes from
47 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_BVR47 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.