Lake San Antonio
Monterey County, California823 acresView mapDirections
SWRCB publishes the water-quality measurements for Lake San Antonio. Here is what has been measured.
- Impaired · Biotoxins
- Limited data
Lake San Antonio in Monterey County, California has water-quality measurements published by SWRCB, shown here as reported. Phosphorus: 350 µg/L. Surface area: 823 acres.
Lake San Antonio is a 823-acre lake in Monterey County, California.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2017-06-26. Methodology: how these readings are compared.
Swimming conditions
No readingBacteria advisory
Nutrient and algae readings are not a swimming clearance. Lake San Antonio is listed impaired under Clean Water Act §303(d) (IR 5) for biotoxins. Check local advisories before you swim.
Whether Lake San Antonio is safe to swim in today is a call for the California State Water Resources Control Board and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lake San Antonio
These are the measurements SWRCB publishes for Lake San Antonio, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Phosphorus 350 µg/L.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | 350µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. |
Ask about Lake San Antonio
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
823 acres
No bathymetric survey has been published for Lake San Antonio, so its depth is not documented here.
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Stays near Lake San Antonio
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Fishing Lake San Antonio
EPA Impairment Status
Lake San Antonio is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Drinking water, Recreation, Other.
Source: EPA ATTAINS assessment unit CAL3098300020080114173957 · Official waterbody report
Nearby Lakes in Monterey County
Frequently asked questions about Lake San Antonio
Where is Lake San Antonio?
- Lake San Antonio is a lake in Monterey County, California. Its water-quality measurements are published by SWRCB and shown on this page as reported.
What is the water quality of Lake San Antonio?
- Lake San Antonio in Monterey County, California has water-quality measurements published by SWRCB, shown here as reported. Phosphorus: 350 µg/L. Surface area: 823 acres.
Is Lake San Antonio safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake San Antonio is listed impaired under Clean Water Act §303(d) (IR 5) for biotoxins. Check local advisories before you swim.
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Where this data comes from
Measurements for Lake San Antonio come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database