Lewiston dam
Lewiston
Lewiston is a Federal-owned dam located in Trinity, California, along the Trinity River. Built in 1963 by the Bureau of Reclamation, this Earth-type dam stands at a height of 73 feet, with a structural height of 91 feet and a length of 745 feet. It serves a primary purpose of water supply, providing a storage capacity of 14,660 acre-feet and covering a surface area of 750 acres.
With a high hazard potential and a moderate risk assessment rating, Lewiston Dam plays a crucial role in managing water resources in the region. Despite not being state-regulated, the Bureau of Reclamation oversees its operations, inspections, and regulatory aspects. The dam's uncontrolled spillway, with a width of 66 feet, further underscores its importance for flood protection and water management in the area. Overall, Lewiston Dam stands as a significant infrastructure for water resource enthusiasts and climate advocates to monitor and study in Trinity County.
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 Lewiston -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Trinity R A Lewiston Ca | 1,090 cfs | → |
| Rush C Nr Lewiston Ca | 18 cfs | → |
| Grass Valley C Nr Lewiston Ca | 18 cfs | → |
| Trinity R Bl Limekiln Gulch Nr Douglas City Ca | 1,210 cfs | → |
| Indian C Nr Douglas City Ca | 28 cfs | → |
| Trinity R A Douglas City Ca | 1,200 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lewiston.
Boat launches
- Rush Creek Road 7542, Trinity County
- Trinity Dam Boulevard Trinity County
- Bucktail Hole
- Fairview Marina Drive, Lewiston
- Granite Peak Road, Trinity Center
- Dump Hole
Campgrounds
Fishing spots
Track Lewiston 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 Lewiston
Where does the data for Lewiston 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 Lewiston.