Almaden Reservoir
Santa Clara County, California52 acresView mapDirections
SWRCB publishes the water-quality measurements for Almaden Reservoir. Here is what has been measured.
- Impaired · Mercury
- 66 ft max depth
- Limited data
Almaden Reservoir in Santa Clara County, California has water-quality measurements published by SWRCB, shown here as reported. Phosphorus: 39 µg/L. Maximum depth: 66 ft. Surface area: 52 acres.
Almaden Reservoir is a 52-acre lake in Santa Clara County, California with a maximum depth of 66 feet (32-foot average).
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2017-12-19. Methodology: how these readings are compared.
What Almaden Reservoir is good for
From access and monitoring records, not editorial picks.
- Deep water66 ft surveyed max depth
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Almaden Reservoir is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Almaden Reservoir 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 Almaden Reservoir
These are the measurements SWRCB publishes for Almaden Reservoir, 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 39 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 | 39µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. |
Ask about Almaden Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
66 ft
Average depth
32 ft
Surface area
52 acres
Shoreline
2.8 mi
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Fishing Almaden Reservoir
EPA Impairment Status
Almaden Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit CAL2054003020000304125701 · Official waterbody report
Nearby Lakes in Santa Clara County
Frequently asked questions about Almaden Reservoir
Where is Almaden Reservoir?
- Almaden Reservoir is a lake in Santa Clara County, California. Its water-quality measurements are published by SWRCB and shown on this page as reported.
What is the water quality of Almaden Reservoir?
- Almaden Reservoir in Santa Clara County, California has water-quality measurements published by SWRCB, shown here as reported. Phosphorus: 39 µg/L. Maximum depth: 66 ft. Surface area: 52 acres.
Is Almaden Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Almaden Reservoir is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
How deep is Almaden Reservoir?
- Almaden Reservoir has a maximum depth of 66 feet and an average depth of 32 feet. The lake covers 52 acres.
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Where this data comes from
Measurements for Almaden Reservoir come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database