Blanchard-Offner dam
Blanchard-Offner
Blanchard-Offner, also known as Lake Rodney, is a private dam located in Napa, California, specifically in the city of Aetna Springs. This earth dam was completed in 1963 and stands at a height of 47 feet, with a hydraulic height of 43 feet. It serves multiple purposes including flood risk reduction, irrigation, recreation, and water supply, with a storage capacity of 274 acre-feet.
Managed by the Natural Resources Conservation Service, Blanchard-Offner has a high hazard potential and is considered to be in satisfactory condition as of the last assessment in September 2017. The dam spans a length of 785 feet and has an associated surface area of 19 acres, with its primary function being flood risk reduction. The dam is regulated and permitted by the California Department of Water Resources, ensuring its safety and compliance with state standards.
Located near Tr Pope Creek, Blanchard-Offner plays a crucial role in managing water resources in the region. Its strategic placement and multiple functions make it a vital infrastructure for the community, safeguarding against floods while providing essential water for irrigation and recreation activities. Enthusiasts of water resources and climate management will find Blanchard-Offner to be a noteworthy example of sustainable infrastructure design and management in California.
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 Blanchard-Offner -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Napa R Nr St Helena Ca | 8 cfs | → |
| Putah C Nr Guenoc Ca | 30 cfs | → |
| Sonoma Creek A Kenwood Ca | 2 cfs | → |
| Maacama C Nr Kellogg Ca | 14 cfs | → |
| Matanzas C A Santa Rosa Ca | 3 cfs | → |
| Santa Rosa C A Santa Rosa Ca | 19 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Blanchard-Offner.
Boat launches
- Chaparral Cove Napa County
- Knoxville Road 1601, Napa County
- Ball Park Avenue 14775, Clearlake
- Napa Valley Vine Trail, Napa
- Island Drive Lake County
- Cuttings Wharf Road 3175-3337, Napa
Campgrounds
- Bothe - Napa Valley State Park
- Napa County Fairgrounds
- Camp Site 1-35
- Camp Site 36-55
- Chaparral Cove - Lake Berryessa - Usbr
- Camp Site 73-100
Fishing spots
Paddle runs
- Cache Creek
- North Fork Cache Creek
- Olema Ranch Campground To Caltrans Corporation Yard At Point Reyes Station
More reservoirs
Track Blanchard-Offner 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 Blanchard-Offner
Where does the data for Blanchard-Offner 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 Blanchard-Offner.