Grizzly Valley dam
Grizzly Valley
Grizzly Valley, located in Portola, California, is a state-regulated dam on the Big Grizzly Creek that serves primarily as a water supply source. Built in 1966, this earth dam stands at a height of 115 feet and has a storage capacity of 83,000 acre-feet, providing essential water resources for the region. With a surface area of 4032 acres and a drainage area of 44 square miles, Grizzly Valley plays a vital role in the local water supply infrastructure.
Despite its age, Grizzly Valley has been deemed to be in satisfactory condition and has a high hazard potential due to its location and the volume of water it can hold. The dam undergoes regular inspections, with the last assessment conducted in October 2020, ensuring its structural integrity and safety. In case of emergencies, the dam's Emergency Action Plan is in place, although details on its preparedness and compliance with guidelines are not provided in the data. Overall, Grizzly Valley remains a crucial asset for water management in the area, supporting both recreation and water supply needs.
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 Grizzly Valley -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Spanish C A Quincy Ca | 53 cfs | → |
| Spanish C Ab Blackhawk C At Keddie Ca | 107 cfs | → |
| Little Truckee R Bl Div Dam Nr Sierraville Ca | 3 cfs | → |
| Independence C Nr Truckee Ca | 34 cfs | → |
| Sagehen C Nr Truckee Ca | 11 cfs | → |
| N Yuba R Bl Goodyears Bar Ca | 549 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Grizzly Valley.
Boat launches
- Salmon Lake -Boat Ramp Boating Site
- Salmon Lake Road 1500, Sierra City
- Sardine Lake Road 990, Sierra City
- Lost Cove Boat Ramp
- Henness Pass Road, Sierraville
- Woodcamp Access Road Nevada County
Campgrounds
- Grizzly Campground
- Lake Davis Dump Station
- Grasshopper Flat .
- Honker Cove Overflow
- Crocker Guard Station
- Crocker .
Fishing spots
Paddle runs
- State Park To Confluence With Middle Fork Feather Wsr
- Gold Lake Highway To Nf Boundary
- Falls To Gold Lake Highway
- Confluence With Squaw Queen Creek To Confluence With Red Clover Creek
- Sec 17, T25n, R14e To Confluence With Last Chance Creek
- Gold Lake Dam To Falls
More reservoirs
Track Grizzly Valley 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 Grizzly Valley
Where does the data for Grizzly Valley 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 Grizzly Valley.