Portal Forebay Main dam
Portal Forebay Main
Portal Forebay Main is a privately owned hydroelectric dam located in Fresno, California. Completed in 1956, this Earth-type dam stands at a height of 65 feet and has a length of 795 feet, with a maximum storage capacity of 390 acre-feet. The dam serves the primary purpose of generating hydroelectric power, utilizing the flow of Camp 61 Creek to produce energy.
Managed by the Federal Energy Regulatory Commission, Portal Forebay Main has a low hazard potential and is inspected every two years to ensure its safety and structural integrity. The dam features an uncontrolled spillway with a width of 100 feet, and its risk assessment is determined to be moderate. Despite its age, the dam's condition assessment is not available, and there are no specific risk management measures outlined for the site.
Located in the picturesque surroundings of Mono Hot Springs, Portal Forebay Main is a key player in California's water resource infrastructure. Its historical significance and ongoing role in hydroelectric power generation make it a noteworthy site for water resource and climate enthusiasts to explore and study.
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 Portal Forebay Main -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Mf San Joaquin R Nr Mammoth Lakes Ca | 579 cfs | → |
| Hot C A Flume Nr Mammoth Lakes Ca | 65 cfs | → |
| Nf Willow C Nr Sugar Pine Ca | 416 cfs | → |
| Deadman C A Big Springs Nr Crestview Ca | 37 cfs | → |
| Big C Div Nr Fish Camp Ca | 0 cfs | → |
| Merced R A Happy Isles Bridge Nr Yosemite Ca | 1,610 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Portal Forebay Main .
Boat launches
- Lake Edison Boating Site
- Florence Lake Boating Site
- Florence Lake Campground
- Huntington Boat Ramp & Launching Site
- Mammoth Pool Rd, California
- Redinger Boating Site
Campgrounds
- Portal Forebay Campground
- Portal Forebay
- Bolsillo Campground
- Mono Hot Springs
- Mono Hot Springs Campground
- Badger Flat Group Campground
Fishing spots
Paddle runs
- Blarney Meadows To South End Of Florence Lake
- Hot Springs Area To West End Of Blarney River
- Confluence With North Fork San Joaquin River To Hells Half Acre
- Northwest Boundary Of Nf/Kings Canyon Np To Hot Springs Area
- Rainbow Falls To Confluence With North Fork San Joaquin River
- Cora Creek To Confluence With San Joaquin River
Track Portal Forebay Main 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 Portal Forebay Main
Where does the data for Portal Forebay Main 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 Portal Forebay Main .