Twin Granite dam
Twin Granite
Twin Granite, also known as Twin Lakes Dam, is a private water resource structure located in Adams County, Idaho. Built in 1920 for irrigation purposes, the dam stands at a height of 24.5 feet and has a hydraulic height of 19.9 feet. With a storage capacity of 600 acre-feet and a surface area of 40 acres, Twin Granite plays a crucial role in managing water resources for agricultural use in the region.
Owned and regulated by the Idaho Department of Water Resources, Twin Granite is classified as a low hazard potential structure with a fair condition assessment. The dam features a controlled spillway with a width of 5 feet and a maximum discharge capacity of 64 cubic feet per second. Despite its age, Twin Granite has undergone regular inspections, with the last assessment conducted in July 2019, ensuring its continued safety and functionality for the community.
Situated along the Twin Lakes and Goose Creek waterways, Twin Granite serves as a vital infrastructure for water management in the area. With its stone core and earth construction, the dam stands as a testament to early 20th-century engineering and continues to play a crucial role in sustaining agricultural activities in the region.
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 Twin Granite -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Nf Payette River At Mccall Id | 1,430 cfs | → |
| Lake Fork Payette River Ab Jumbo Cr Nr Mccall Id | 588 cfs | → |
| Little Salmon River At Riggins Id | 2,420 cfs | → |
| Sf Salmon River Nr Krassel Ranger Station Id | 2,190 cfs | → |
| Snake River At Hells Canyon Dam Id-Or State Line | 19,200 cfs | → |
| Johnson Creek At Yellow Pine Id | 2,140 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Twin Granite.
Boat launches
- Grouse Creek Campground Road Adams County
- Fisher Creek Road Adams County
- Granite Lake Dam Road Valley County
- Warren Wagon Road Mccall
- National Forest Development Road 1614 Idaho County
- Salmon River Road Idaho County
Campgrounds
- Goose Lake Camping Area
- Grouse Campground
- Grouse
- Granite Lake Camping Area
- Brundage Reservoir Camping Area
- Hazard Lake
Fishing spots
Paddle runs
- Headwaters At Hard Creek Lake To Payette Nf Boundary
- Hard Creek
- Headwaters To Confluence With Vance Creek At Payette Nf Boundary
- Hazard Creek
- French Creek
- Payette Nf Boundary On Lake Creek (Just West Marshall Lake) To To And Including Chinook Campground
More reservoirs
Track Twin Granite 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 Twin Granite
Where does the data for Twin Granite 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 Twin Granite.