Upper Oso dam
Upper Oso
Upper Oso, located in Mission Viejo, Orange County, California, is a key water resource infrastructure managed by a public utility. This earth dam, completed in 1979, stands tall at 142 feet, with a hydraulic height of 135 feet, serving multiple purposes including flood risk reduction, irrigation, and water supply. With a storage capacity of 3,700 acre-feet and a drainage area of 1.13 square miles, Upper Oso plays a crucial role in managing water resources in the region.
The dam, situated on Oso Creek, is under the regulatory oversight of the California Department of Water Resources for safety and inspection. Despite its satisfactory condition assessment, Upper Oso poses a high hazard potential, necessitating regular inspections and emergency preparedness measures. In the event of any emergencies, the dam operators are required to follow established protocols for ensuring public safety and mitigating risks associated with its operation.
As a vital component of the water supply infrastructure in the area, Upper Oso underscores the importance of sustainable water management practices in the face of changing climate patterns. With a focus on ensuring the dam's integrity and functionality, stakeholders continue to monitor its performance and implement necessary risk management measures to safeguard against potential hazards and support the water needs of the local community.
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.
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 Upper Oso -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Agua Chinon Wash Nr Irvine Ca | · | → |
| Sand Cyn C A Irvine Ca | 0 cfs | → |
| Arroyo Trabuco A San Juan Capistrano Ca | 2 cfs | → |
| Temescal C A Corona Lk Nr Corona Ca | · | → |
| Bonita C A Irvine Ca | 1 cfs | → |
| Santa Ana R Bl Prado Dam Ca | 114 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Upper Oso.
Boat launches
- Vacation Drive 28736, Canyon Lake
- Goetz Road Riverside County
- Granada Launch Ramp - Long Beach
- Eucalyptus Park Road, San Dimas
Campgrounds
- Oso Lake Scout Camp
- Oneill Regional Park
- Lazy-W-Ranch Camp
- Owl/Quail Group Campground
- Starr Mesa Equestrian Campground
- Caspers Wilderness Park
Fishing spots
- Laguna Niguel Lake
- Irvine Lake (Santiago Res)
- Corona Lake
- Elsinore Lake
- Lake Elsinore
- Santa Ana River Lakes
Paddle runs
- San Mateo Wilderness Boundary To Nf Boundary With Camp Pendleton
- Devil Canyon Tributary To San Mateo Creek
- Santa Margarita River
- Middle Fork - Commanche Campsite To Middle Fork Trailhead
- Laurel Gulch To Confluence With Mineo Canyon (Se 1/4, Sw 1/4, Sec 17, T2n, R8w)
More reservoirs
Track Upper Oso in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About Upper Oso
Where does the data for Upper Oso 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 above 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.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Upper Oso.