Gem Lake dam
Gem Lake
Gem Lake, located in Mono County, California, is a private hydroelectric dam constructed in 1917 by L.R. Jorgensen. The dam stands at a height of 80 feet and has a capacity of 17,228 acre-feet, serving as a vital source of water storage for the surrounding area. With a maximum discharge of 1,700 cubic feet per second, Gem Lake plays a crucial role in regulating water flow and providing hydroelectric power to the region.
The dam's primary purpose is hydroelectric generation, but it also offers recreational opportunities for visitors to enjoy. Situated on Rush Creek, the dam spans 688 feet in length and covers a surface area of 282 acres. Despite its age, Gem Lake Dam is regularly inspected and regulated by both state and federal agencies to ensure its structural integrity and safety. With a high hazard potential and moderate risk assessment, the dam remains a key feature in the water resource management and climate resilience efforts in the area.
Gem Lake Dam is a testament to the intersection of human ingenuity and natural resource management, showcasing the importance of sustainable hydroelectric infrastructure in a changing climate. As water resource and climate enthusiasts, understanding the significance of structures like Gem Lake Dam is crucial in safeguarding our water supply and adapting to environmental challenges. With its rich history and continued utility, Gem Lake Dam stands as a symbol of resilience and innovation in the face of evolving climate conditions.
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 Gem Lake -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Mf San Joaquin R Nr Mammoth Lakes Ca | 595 cfs | → |
| Deadman C A Big Springs Nr Crestview Ca | 37 cfs | → |
| Hot C A Flume Nr Mammoth Lakes Ca | 65 cfs | → |
| Merced R A Happy Isles Bridge Nr Yosemite Ca | 1,730 cfs | → |
| Merced R A Pohono Bridge Nr Yosemite Ca | 2,040 cfs | → |
| Green Creek Near Bridgeport | 60 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Gem Lake .
⚓ Boat launches
- Gull Meadows Car Top Boat Launch
- Navy Beach Paddle Boat Launch
- Lake Edison Boating Site
- Mammoth Pool Rd, California
⛺ Campgrounds
- Silver Lake - June Lake
- Reversed Creek Campground
- Reversed Creek
- Gull Lake Campground
- Gull Lake
- Aerie Crag Picnic Area
🎣 Fishing spots
More fishing →🛶 Paddle runs
- Headwaters At Thousand Island Lake To Agnew Meadows
- Headwaters To Wilderness Boundary
- Headwaters To Walker Lake
- Confluence With Glass Creek To Big Springs
- National Monument Boundary To Soda Springs Footbridge In Devils Postpile National Monument
- Agnew Meadows To Soda Springs Footbridge
🛡 More reservoirs
More reservoirs →Track Gem 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 Gem Lake
Where does the data for Gem 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 Gem Lake .