Hansen Dam dam
Hansen Dam
Hansen Dam, also known as Hansen Reservoir, is a Federal-owned Earth dam in Los Angeles, California, constructed by the US Army Corps of Engineers in 1940 for flood risk reduction along the Tujunga Wash. With a height of 97 feet and a storage capacity of 44,990 acre-feet, the dam plays a crucial role in protecting downstream cities like Los Angeles, Burbank, and Glendale from potential flooding. Despite its high hazard potential, USACE has implemented various risk management measures to ensure public safety, including regular inspections, monitoring, and maintenance.
A risk assessment conducted in 2008 identified Hansen Dam as having a moderate risk level due to potential dam instability, structural concerns, and the possibility of embankment erosion during extreme flood events. The dam's failure could have significant consequences on over 300,000 people and cause substantial economic impacts. To mitigate these risks, USACE collaborates closely with state and local emergency managers, conducts emergency exercises, and regularly updates its Emergency Action Plan. Additionally, the agency engages with local communities to enhance flood preparedness and communication strategies.
Looking ahead, USACE plans to reevaluate and update the project risk assessment in 2022 to ensure the most accurate risk response measures are in place. By continuing to monitor and maintain Hansen Dam, implementing proactive risk communication strategies, and working closely with stakeholders, USACE aims to safeguard the surrounding communities and infrastructure from the potential impacts of dam failure and extreme flooding events.
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 Hansen Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Big Tujunga C Bl Hansen Dam Ca | · | → |
| Los Angeles R A Sepulveda Dam Ca | 78 cfs | → |
| Arroyo Seco Nr Pasadena Ca | 6 cfs | → |
| Santa Clara R Nr Piru Ca | 71 cfs | → |
| Rio Hondo Ab Whittier Narrows Dam Ca | 65 cfs | → |
| Rio Hondo Bl Whittier Narrows Dam Ca | 11 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Hansen Dam.
Campgrounds
- Tom Lucas Trailcamp
- Group Campground 6
- Group Campground 5
- Group Campground 4
- Group Campground 3
- Group Campground 2
Fishing spots
Paddle runs
- West Fork - Headwaters (Se 1/4, Ne 1/4, Sec 14, T2n, R12w) To Cogswell Reservoir (Ne 1/4, Sw 1/4, Sec 24, T2n, R9w
- Site Of St Francis Dam Disaster To Seco Canyon At The Nf Boundary
- Gaging Station Below Spillway Of Cogswell Dam (Ne 1/4, Se 1/4, Sec 19, T2n, R10w) To Confluence With Nf San Gabriel River (Sw 1/4.Sw 1/4, Sec 15, T2n, R9w)
- Green Valley At The Nf Boundary To Site Of St Francis Dam Disaster
- Mainstream - Confluence With South Fork Little Rock Creek To Little Rock Creek Reservoir
- Cooper Canyon- Near State Highway 2 (Sw 1/4, Ne 1/4, Sec 16, T3n, R10w To Confluence With Little Rock Creek
Track Hansen Dam 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 Hansen Dam
Where does the data for Hansen Dam 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 Hansen Dam.