South Mountain Reservoir
South Mountain Reservoir in Modoc County, California is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 186 acres.
- Area
- 186 acres
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Why South Mountain Reservoir 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 South Mountain Reservoir, no water-quality sampling on record for this lake.
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 your state environmental agency and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
South Mountain Reservoir is a 186-acre lake in Modoc County, California.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled recent years. Grade methodology: LakeQuality methodology.
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Swimming Safety
Not ratedElevated nutrients
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for South Mountain Reservoir
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Trophic State Index: undefined.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) |
Where to stay near South Mountain Reservoir
Compare lakeside cabins, hotels, and vacation rentals near South Mountain Reservoir in Modoc 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.
Top-rated places to stay near South Mountain Reservoir
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 186 acres |
No bathymetric survey has been published for South Mountain Reservoir, so its depth is not documented here.
Fishing South Mountain Reservoir
Nearby Lakes in Modoc County
Frequently asked questions about South Mountain Reservoir
Where is South Mountain Reservoir?
- South Mountain Reservoir is a lake in Modoc County, California. LakeQuality has not rated this lake (UNRATED) — no water-quality sampling on record for this lake.
What is the water quality grade for South Mountain Reservoir?
- South Mountain Reservoir in Modoc County, California is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 186 acres.
Is South Mountain Reservoir safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. South Mountain Reservoir is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
Explore South Mountain Reservoir across LakeQuality
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Where this data comes from
Measurements for South Mountain Reservoir come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.