Lake Mary dam
Lake Mary
Lake Mary, located in Mono County, California, is a Federal-owned water supply reservoir managed by the Forest Service. Built in 1934, this Earth dam stands at a height of 10 feet and has a storage capacity of 1300 acre-feet. The primary purpose of Lake Mary is to provide water supply, with additional benefits including flood risk reduction and recreation opportunities.
Despite its relatively small size, Lake Mary plays a critical role in the region's water resource management and is classified as having a high hazard potential. With a drainage area of 7.73 square miles, the reservoir serves as a vital source of water for surrounding communities. The dam features a controlled spillway and flap outlet gates, with periodic inspections and maintenance to ensure its structural integrity.
Although the condition assessment is currently listed as "Not Rated," the risk assessment for Lake Mary is categorized as very high. The reservoir's risk management measures and emergency action plan status are not specified, suggesting potential areas for improvement in ensuring the safety and reliability of this essential water supply infrastructure. As climate change continues to impact water resources, the conservation and proper maintenance of Lake Mary are crucial for meeting the region's growing water demands and adapting to changing environmental 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 Lake Mary -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Mf San Joaquin R Nr Mammoth Lakes Ca | 278 cfs | → |
| Deadman C A Big Springs Nr Crestview Ca | 33 cfs | → |
| Hot C A Flume Nr Mammoth Lakes Ca | 64 cfs | → |
| Merced R A Happy Isles Bridge Nr Yosemite Ca | 725 cfs | → |
| Nf Willow C Nr Sugar Pine Ca | 416 cfs | → |
| Big C Div Nr Fish Camp Ca | 0 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lake Mary.
Boat launches
- Gull Meadows Car Top Boat Launch
- Lake Edison Boating Site
- Florence Lake Boating Site
- Florence Lake Campground
- Navy Beach Paddle Boat Launch
- Mammoth Pool Rd, California
Campgrounds
Fishing spots
Paddle runs
- Rainbow Falls To National Monument Boundary
- Soda Springs Footbridge In Devils Postpile National Monument To Rainbow Falls
- Agnew Meadows To Soda Springs Footbridge
- National Monument Boundary To Soda Springs Footbridge In Devils Postpile National Monument
- Wilderness Boundary To La Dept. Of Water And Power Property
- Headwaters At Thousand Island Lake To Agnew Meadows
More reservoirs
Track Lake Mary 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 Mary
Where does the data for Lake Mary 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 Mary.