Lake Anza
Contra Costa County, California10 acresView mapDirections
SWRCB publishes the water-quality measurements for Lake Anza. Here is what has been measured.
- Limited data
Lake Anza in Contra Costa County, California has water-quality measurements published by SWRCB, shown here as reported. Water clarity: 12.3 ft visibility. Surface area: 10 acres.
Lake Anza is a 10-acre lake in Contra Costa County, California.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2023-07-25. Methodology: how these readings are compared.
What Lake Anza is good for
From access and monitoring records, not editorial picks.
- Clear water12.3 ft of visibility
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Lake Anza 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 Anza
These are the measurements SWRCB publishes for Lake Anza, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 12.3 ft. TSI 41.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 12.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading 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. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 41 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Lake Anza
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
10 acres
No bathymetric survey has been published for Lake Anza, so its depth is not documented here.
Stays via Stay22
Stays near Lake Anza
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Top-rated places to stay near Lake Anza
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Fishing Lake Anza
Reservoir Info (USACE NID)
Lake Anza is a man-made reservoir impounded by the C.L. Tilden Park (completed 1938), built primarily for other on the Wildcat Creek; earth-type dam, 88 ft tall and 355 ft long.
- Surface area
- 10 ac
- Max storage
- 268 ac-ft
- Drainage area
- 1.56 sq mi
- Hazard class
- High
- Owner
- East Bay Regional Park District
All listed purposes: Other;Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID CA00161 · Operator website · Matched by proximity (0.19 km)
Nearby Lakes in Contra Costa County
Frequently asked questions about Lake Anza
Where is Lake Anza?
- Lake Anza is a lake in Contra Costa County, California. Its water-quality measurements are published by SWRCB and shown on this page as reported.
What is the water quality of Lake Anza?
- Lake Anza in Contra Costa County, California has water-quality measurements published by SWRCB, shown here as reported. Water clarity: 12.3 ft visibility. Surface area: 10 acres.
Is Lake Anza safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Lake Anza across LakeQuality
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Mesotrophic Lakes in California
Where this data comes from
3 measurements from 1 monitoring station, 2021–2023. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- North American Lake Management Society
NALMS3 samples · 2021–2023
Monitoring station identifiers (1)
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.