Lyons dam
Lyons
Located in Tuolumne County, California, Lyons is a private hydroelectric dam on the South Fork Stanislaus River. Completed in 1930, this concrete arch dam stands at a height of 132 feet and spans 535 feet in length, providing essential services such as fire protection, irrigation, and hydroelectric power generation. With a maximum storage capacity of 6,228 acre-feet and a drainage area of 66.8 square miles, Lyons plays a crucial role in managing water resources in the region.
Managed by the Federal Energy Regulatory Commission, Lyons has a controlled spillway width of 284 feet and four Tainter radial gates. The dam's hazard potential is classified as high, with a very high risk assessment rating. While the condition assessment is not available, regular inspections and enforcement by state agencies ensure its operational safety and compliance with regulations. As a key structure in the water infrastructure of California, Lyons exemplifies the intersection of water resource management and climate resilience in the face of varying environmental challenges.
The dam's location in Long Barn, California, and its role in the conservation of water resources highlight the importance of sustainable practices and infrastructure investment in mitigating the impacts of climate change. With its historical significance and continued operation under state jurisdiction, Lyons stands as a testament to the ongoing efforts to balance water resource utilization with environmental conservation in the face of evolving climate patterns. For water resource and climate enthusiasts, Lyons offers a fascinating case study in the intersection of engineering, policy, and environmental stewardship.
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 Lyons -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Cherry C Bl Valley Dam Nr Hetch Hetchy Ca | 7 cfs | → |
| Big C Ab Whites Gulch Nr Groveland Ca | 1 cfs | → |
| Lk Eleanor Div To Cherry Lake Nr Hetch Hetchy Ca | 1 cfs | → |
| Cherry C Bl Dion R Holm Ph | 233 cfs | → |
| Cherry C Nr Early Intake Ca | 205 cfs | → |
| Eleanor C Nr Hetch Hetchy Ca | 81 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lyons .
Boat launches
- Forest Route 1n04, Groveland
- Forest Route 1n10 Tuolumne County
- Merals Pool Put-In
- Glory Hole Road 6503, Angels Camp
Campgrounds
Fishing spots
Paddle runs
- Clavey River At Confluence Of Bell And Lily Creeks To 3n01
- Clavey River From 3n01 To Cottonwood Road
- Sandbar To Confluence With North Fork Stanislaus River
- 0.15 Mile Downstream From Road 4n26b To Confluence With Lilly Creek
- Below Mckay's Reservoir To Confluence With Middle Fork Stanislaus River
- Confluence With North Fork And Middle Fork Stanislaus To Clark Flat
Track Lyons 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 Lyons
Where does the data for Lyons 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 Lyons .