San Diego Reservoir Dam
San Diego Reservoir
San Diego Reservoir, located in Tuolumne, California, is a vital water resource structure that serves as a primary water supply for the region. Built in 1860, this earth dam stands at a height of 39 feet, with a hydraulic height of 35 feet, and a length of 155 feet. With a storage capacity of 40 acre-feet and a surface area of 5 acres, the reservoir plays a critical role in irrigation, recreation, and water supply for the area.
Managed by a public utility, San Diego Reservoir is regulated by the California Department of Water Resources (DWR) for safety compliance. The dam is inspected regularly, with the last assessment in February 2021 determining a satisfactory condition. While it has a significant hazard potential, due to its age and design, the structure is deemed to be in a satisfactory state, meeting regulatory guidelines and ensuring the safety of surrounding communities.
The reservoir, situated on Tr Mormon Cr river, is a key component of the water infrastructure in the region, providing essential resources for agricultural and domestic use. With its historical significance and ongoing maintenance, San Diego Reservoir continues to be a crucial asset in water management and climate resilience efforts in the area.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around San Diego Reservoir -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Black C Nr Copperopolis Ca | · | → |
| Big C Ab Whites Gulch Nr Groveland Ca | · | → |
| Cherry C Bl Dion R Holm Ph | 98 cfs | → |
| Tuolumne R Bl Early Intake Nr Mather Ca | 136 cfs | → |
| Cherry C Nr Early Intake Ca | 39 cfs | → |
| Tuolumne R Bl Lagrange Dam Nr Lagrange Ca | 189 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near San Diego Reservoir.
Boat launches
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Campgrounds
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Fishing spots
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River runs
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About San Diego Reservoir
Where does the data for San Diego Reservoir come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the Significant hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card below for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.