Lower Twin Lake dam
Lower Twin Lake
Lower Twin Lake, located in Mono County, California, is a private water supply dam with a history dating back to its completion in 1888. The dam, primarily serving irrigation and water supply purposes, stands at a height of 16 feet with a hydraulic height of 11.7 feet. It stores a maximum capacity of 4011 acre-feet of water and covers a surface area of 399 acres, drawing from a drainage area of 39.1 square miles.
Managed by the California Department of Water Resources (DWR) and regulated for safety by the Safety of Dams agency, Lower Twin Lake's dam has a high hazard potential but is currently rated in fair condition as of the last assessment in September 2017. The dam's emergency action plan was last revised in August 2019, ensuring preparedness in the event of a crisis. With a recent inspection in October 2020 and a regular inspection frequency of 1 year, the dam remains under careful monitoring to ensure its structural integrity and continued safe operation.
Surrounded by the stunning scenery of Bridgeport and fed by Robinson Creek, Lower Twin Lake stands as a vital resource for water supply and agricultural irrigation in the region. Its historical significance, coupled with its ongoing regulatory oversight and maintenance efforts, highlights the importance of sustainable water management practices in the face of changing climate conditions. Enthusiasts of water resources and climate resilience can appreciate the role that Lower Twin Lake plays in balancing human needs with environmental stewardship in California's diverse landscape.
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 Lower Twin Lake -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Robinson C At Twin Lks Outlet Nr Bridgeport | 128 cfs | → |
| Buckeye C Nr Bridgeport | 103 cfs | → |
| Green Creek Near Bridgeport | 47 cfs | → |
| E Walker R Nr Bridgeport | 169 cfs | → |
| W Walker R Blw L Walker R Nr Coleville | 627 cfs | → |
| E Walker R Blw Sweetwater C Nr Bridgeport | 22 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lower Twin Lake.
Boat launches
Campgrounds
- Lower Twin Lake
- Lower Twin Lake Campground
- Paha
- Robinson Creek
- Paha Campground
- Robinson Creek South/North Campground
Fishing spots
Track Lower Twin Lake 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 Lower Twin Lake
Where does the data for Lower Twin Lake 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 Lower Twin Lake.