Long Valley dam
Long Valley
Long Valley, also known as Crowley Lake, is a local government-owned water resource nestled in the picturesque Mono County, California. It stands as a vital structure along the Owens River, serving as a key component in the state's water supply infrastructure. Completed in 1941, this earth dam stands at an impressive height of 126 feet, with a storage capacity of 183,465 acre-feet.
With a primary purpose of water supply, Long Valley also caters to hydroelectric power generation and recreational activities. Its strategic location in the city of Bishop makes it a hub for water enthusiasts and climate advocates alike. Despite its high hazard potential, the dam's condition assessment remains satisfactory, ensuring the safety and integrity of this critical water management system.
Managed by the Department of Water Resources and the Safety of Dams agency, Long Valley undergoes regular inspections and enforcement to guarantee its operational efficiency. With a vast drainage area of 437 square miles and a surface area of 5,280 acres, this dam plays a crucial role in water conservation and management in the region. For those passionate about water resources and climate resilience, Long Valley stands as a remarkable example of sustainable infrastructure supporting both environmental and societal needs.
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 Long Valley -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Hot C A Flume Nr Mammoth Lakes Ca | 56 cfs | → |
| Deadman C A Big Springs Nr Crestview Ca | 38 cfs | → |
| Mf San Joaquin R Nr Mammoth Lakes Ca | 531 cfs | → |
| Merced R A Happy Isles Bridge Nr Yosemite Ca | 1,480 cfs | → |
| Nf Willow C Nr Sugar Pine Ca | 416 cfs | → |
| Green Creek Near Bridgeport | 65 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Long Valley.
Boat launches
- Lake Edison Boating Site
- Gull Meadows Car Top Boat Launch
- Florence Lake Campground
- Florence Lake Boating Site
- Navy Beach Paddle Boat Launch
Campgrounds
Fishing spots
Paddle runs
- Wilderness Boundary To Tom's Place
- Tom's Place To Nf Boundary
- Headwaters To Wilderness Boundary
- Lower Rock Creek
- Hot Creek
- Fish Hatchery To Nf Boundary
More reservoirs
Track Long Valley 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 Long Valley
Where does the data for Long Valley 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 Long Valley.