Beardsley Afterbay dam
Beardsley Afterbay
Beardsley Afterbay, located in Sonora, California, serves as a vital hydroelectric resource along the Middle Fork Stanislaus River. Built in 1958, this rockfill dam stands at a height of 33 feet, containing a maximum storage capacity of 355 acre-feet. With a primary purpose of hydroelectric power generation, Beardsley Afterbay plays a crucial role in providing sustainable energy to the region.
Managed by a public utility entity and regulated by the Department of Water Resources and the Federal Energy Regulatory Commission, Beardsley Afterbay boasts a low hazard potential and moderate risk assessment rating. Despite its age, the dam has undergone regular inspections and meets state jurisdiction and permitting requirements. While the spillway type is uncontrolled, the dam's structural integrity remains sound, ensuring the safety of the surrounding communities.
With its picturesque surroundings and functional design, Beardsley Afterbay stands as a testament to the intersection of water resource management and climate sustainability. As a key player in the local hydroelectric infrastructure, this dam continues to harness the power of the Middle Fork Stanislaus River while adhering to stringent regulatory standards and ensuring the safety of its operations.
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 Beardsley Afterbay -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Cherry C Bl Valley Dam Nr Hetch Hetchy Ca | 6 cfs | → |
| Lk Eleanor Div To Cherry Lake Nr Hetch Hetchy Ca | 1 cfs | → |
| Eleanor C Nr Hetch Hetchy Ca | 46 cfs | → |
| Cherry C Nr Early Intake Ca | 55 cfs | → |
| Cherry C Bl Dion R Holm Ph | 1,130 cfs | → |
| Tuolumne R Bl Early Intake Nr Mather Ca | 1,390 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Beardsley Afterbay .
Boat launches
- Forest Route 1n04, Groveland
- Forest Route 1n10 Tuolumne County
- Merals Pool Put-In
- Glory Hole Road 6503, Angels Camp
- Amador County
Campgrounds
- Beardsley Dam
- Beardsley Dam Campground
- Teleli Pulaya (Black Oak) Campground
- Fraser Flat Campground
- Fraser Flat
- Sand Bar Flat
Fishing spots
Paddle runs
- 0.15 Mile Downstream From Road 4n26b To Confluence With Lilly Creek
- One-Tenth Mile Downstream Of Coffin Hollow To Confluence With Bell Creek And Clavey River
- Lilly Creek (Source At Chewing Gum Lake And Y Meadow Lake) To One-Tenth Mile Downstream Of Coffin Hollow
- Clavey River At Confluence Of Bell And Lily Creeks To 3n01
- One-Tenth Mile Upstream Of Crabtree Trailhead To 0.15 Mile Downstream Of Road 4n26b
- Bell Creek Headwaters To One-Tenth Mile Upstream Of Crabtree Trailhead
Track Beardsley Afterbay 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 Beardsley Afterbay
Where does the data for Beardsley Afterbay 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 Low 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 Beardsley Afterbay .