Lake Valley Main dam
Lake Valley Main
Lake Valley Main is a privately owned dam located in Placer, California, in the city of Washington. Built in 1889 for hydroelectric purposes, this earth dam stands at a height of 75 feet and spans a length of 1035 feet. With a storage capacity of 7964 acre-feet and a normal storage of 7700 acre-feet, the dam holds back the waters of the North Fork American River, covering a surface area of 298 acres and serving a drainage area of 4.5 square miles.
Managed by the Federal Energy Regulatory Commission, Lake Valley Main is deemed to have a high hazard potential, with a maximum discharge capacity of 5200 cubic feet per second. While the dam lacks a spillway, its inspection, enforcement, and regulatory oversight are carried out by both state and federal agencies. Despite its age, the dam remains in operational condition, with the last inspection conducted in September 2020. With its historical significance and vital role in hydroelectric power generation, Lake Valley Main stands as a testament to the importance of sustainable water resource management in the face of climate change challenges.
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 Lake Valley Main -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Donner C A Donner Lk Nr Truckee Ca | 10 cfs | → |
| Little Truckee R Bl Div Dam Nr Sierraville Ca | 3 cfs | → |
| Independence C Nr Truckee Ca | 10 cfs | → |
| Donner C At Hwy 89 Nr Truckee Ca | 88 cfs | → |
| Truckee R Nr Truckee Ca | 519 cfs | → |
| Sagehen C Nr Truckee Ca | 13 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lake Valley Main.
Boat launches
- Lake Spaulding Road 10260, Nevada City
- Fuller Lake Boating Site
- Meadow Lake Road Nevada County
- Woodcamp Access Road Nevada County
- Henness Pass Road, Sierraville
- Iowa Hill Road Placer County
Campgrounds
- Lake Spaulding Campground
- Lake Spaulding
- Donner Summit Area - Lake Spaulding
- Indian Springs Campground
- Cisco Grove Campground, Tubing, And Rv Park
- Campsite - Metal Bench
Fishing spots
Paddle runs
- Langs Crossing Bridge To One-Half Mile West Of Confluence With Fall Creek (Boundary Of Nf And Private Land)
- Generation And Giant Gaps (Tadpole To Colfax-Iowa Hill Road)
- One-Half Mile West Of Confluence With Fall Creek To Confluence With Jefferson Creek
- Royal Gorge (Soda Springs To Tadpole Creek)
- Interbay To Oxbow (End Of The World)
- Hell Hole Dam To Ellicotts Bridge
Track Lake Valley Main 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 Lake Valley Main
Where does the data for Lake Valley Main 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 Lake Valley Main.