Willow Lake #1 dam
Willow Lake #1
Willow Lake #1, located in Napa, California, is a privately owned earth dam completed in 2004 for flood risk reduction along the Tr Napa River. Standing at a height of 40 feet with a hydraulic height of 34 feet, this dam has a storage capacity of 89 acre-feet and covers a surface area of 6 acres. Despite its high hazard potential, the dam is currently in satisfactory condition and has been regularly inspected by the California Department of Water Resources.
The primary purpose of Willow Lake #1 is flood risk reduction, but it also serves for irrigation and water supply in the region. With its proximity to the Napa River, the dam plays a crucial role in managing water resources and protecting the surrounding areas from potential flooding events. The dam has state jurisdiction, permitting, inspection, and enforcement, ensuring its compliance with safety regulations and standards to safeguard the community and the environment.
Led by its primary owner, this dam continues to play a vital role in the water resource management of Napa County. With a solid foundation and a robust structure, Willow Lake #1 stands as a testament to the importance of sound infrastructure in mitigating flood risks and ensuring water supply for agricultural and urban needs in the region. As climate change poses new challenges to water management, the significance of dams like Willow Lake #1 only grows, highlighting the essential role they play in adapting to a changing climate and safeguarding water resources for future generations.
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 Willow Lake #1 -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Nathanson C A Sonoma Ca | 0 cfs | → |
| Napa R Nr Napa Ca | 27 cfs | → |
| Sonoma C A Agua Caliente Ca | 10 cfs | → |
| Sonoma Creek A Kenwood Ca | 2 cfs | → |
| Napa R Nr St Helena Ca | 8 cfs | → |
| Petaluma R A Copland Pumping Station A Petaluma Ca | 90 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Willow Lake #1.
Boat launches
- Napa Valley Vine Trail, Napa
- Cuttings Wharf Road 3175-3337, Napa
- Cuttings Wharf Road 3270, Napa
- North Camino Alto Vallejo
- Curtola Parkway 139-199, Vallejo
- Sears Point Road 100-138, Novato
Campgrounds
- Napa Valley Expo
- Skyline Wilderness County Park
- Camp Via (Sonoma Developmental Center)
- Browers Garden Camping - No Reservation Needed
- Rowser Garden Camping (No Reservation Needed)
- Sugarloaf Ridge State Park
Fishing spots
- 9th Street Boat Ramp
- City Of Benicia Fishing Pier
- Lake Ralphine
- Lake Berryessa
- Berryessa Lake
- San Pablo Reservoir
Paddle runs
- Headwaters To Ends One Quarter Mile South Of Bear Valley Road Bridge Segment 1: Ends 1/4 Mile South Of Bear Valley Road Bridge Segment 2: Caltrans Corporation Yard At Point Reyes Staton.
- Headwaters To Mouth
- Olema Ranch Campground To Caltrans Corporation Yard At Point Reyes Station
- Cache Creek
Track Willow Lake #1 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 Willow Lake #1
Where does the data for Willow Lake #1 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 Willow Lake #1.