Isabel Lake No. 1
Isabel Lake No. 1 is an earth dam located in Santa Clara County, California, built in 1948. It carries a Low hazard potential classification and has a satisfactory condition assessment.
About Isabel Lake No. 1
The primary purpose of Isabel Lake No. 1 is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by O'neal, Swenson And Mcdonald (private). It impounds the Tr Isabel Creek.
The dam stands 23 feet tall and stretches 990 feet across, creates a reservoir covering 46 acres, and has a maximum storage capacity of 435 acre-feet. Completed in 1948, the structure is well-established, with more than 75 years of service.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. The most recent inspection on record was 06/06/2025.
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Location
| State | California |
| County | Santa Clara |
| River/Stream | Tr Isabel Creek |
| Coordinates | 37.31790, -121.53960 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 23 ft |
| Dam Height | 23 ft |
| Dam Length | 990 ft |
| Year Completed | 1948 (78 years old) |
Storage & Hydraulics
| NID Storage | 435 acre-ft |
| Max Storage | 435 acre-ft |
| Surface Area | 46 acres |
Ownership & Safety
| Purpose | Water Supply |
| Owner | O'Neal, Swenson and McDonald |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/06/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | CA01238 |
| Federal ID | CA01238 |
| More Info | State Dam Safety Program |