Hidden Dam dam
Hidden Dam
Hidden Dam, also known as Hensley Lake, is a Federal-owned structure located in Madera, California. Built in 1975 by the US Army Corps of Engineers, the dam stands at 140 feet tall and has a maximum storage capacity of 116,727 acre-feet. Its primary purpose is flood risk reduction, but it also serves for hydroelectric power generation, irrigation, and recreation. The dam is situated on the Fresno River and covers a surface area of 1570 acres.
With a high hazard potential, Hidden Dam is continuously monitored and managed by the US Army Corps of Engineers to mitigate flood risks. The agency regularly inspects the dam, updates emergency action plans, and collaborates with local emergency managers to ensure preparedness in case of a dam-related emergency. Despite its risk management measures, the dam's limited water storage capacity and the potential for severe weather events to overwhelm the system highlight the importance of ongoing vigilance and maintenance. As the agency works to address all types of flood risks associated with the dam, additional details specific to Hidden Dam will be provided in the future to enhance understanding and preparedness.
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 Hidden Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| San Joaquin R Bl Friant Ca | 476 cfs | → |
| Nf Willow C Nr Sugar Pine Ca | 416 cfs | → |
| Big C Div Nr Fish Camp Ca | 0 cfs | → |
| San Joaquin R Nr Mendota Ca | 149 cfs | → |
| Merced R A Pohono Bridge Nr Yosemite Ca | 1,280 cfs | → |
| Merced R A Happy Isles Bridge Nr Yosemite Ca | 806 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Hidden Dam.
Boat launches
- Madera County
- Road 29 Madera County
- County Road 29 Madera County
- San Joaquin River Trail, Friant
- Redinger Boating Site
Campgrounds
- Hidden View
- Hidden View Campground
- Wildcat Primitive Campground
- Codorniz Rec Area
- Cordoniz Group Area South
- Cordoniz Campground
Fishing spots
Paddle runs
- Confluence With North Fork San Joaquin River To Hells Half Acre
- Cora Creek To Confluence With San Joaquin River
- Rainbow Falls To Confluence With North Fork San Joaquin River
- Hemlock Crossing To Confluence With Cora Creek
- Headwaters Near The Tuolumne And Mariposa County Lines To Western Boundary Of Yosemite National Park
- Confluence With Middle Fork Tuolumne River To Confluence With Tuolumne River
More reservoirs
Track Hidden Dam 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 Hidden Dam
Where does the data for Hidden Dam 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 Hidden Dam.