Modesto Reservoir Dam
Modesto Reservoir
Modesto Reservoir, located in Modesto, California, is a vital water resource infrastructure primarily used for irrigation and water supply purposes. Constructed in 1911, this Earth-type dam stands at a height of 36 feet and has a storage capacity of 40,000 acre-feet, serving the needs of the local community and surrounding agricultural areas. The reservoir is situated on the Tuolumne River, covering a surface area of 3,800 acres and draining an area of 10 square miles.
Managed by a public utility agency, Modesto Reservoir is regulated and inspected by the California Department of Water Resources for safety and compliance. Despite its high hazard potential due to its critical role in water supply, the dam's condition assessment in 2017 reported it as satisfactory. With a recent inspection in March 2021 and an emergency action plan prepared, the reservoir is equipped to handle potential risks and emergencies effectively. As a significant water infrastructure in the region, Modesto Reservoir plays a crucial role in ensuring water security and resource sustainability for the local community and beyond.
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 Modesto Reservoir -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Modesto Cn Nr La Grange Ca | 1,230 cfs | → |
| Tuolumne R Bl Lagrange Dam Nr Lagrange Ca | 193 cfs | → |
| Turlock Cn Nr La Grange Ca | 1,560 cfs | → |
| Tuolumne R A Modesto Ca | 187 cfs | → |
| Black C Nr Copperopolis Ca | · | → |
| Stanislaus R A Ripon Ca | 253 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Modesto 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 Modesto Reservoir
Where does the data for Modesto 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 High 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.