Alder dam
Alder
Alder is a captivating hydroelectric dam located on the Nisqually River in Yelm, Washington. Completed in 1945, this concrete structure stands at a towering height of 285 feet, with a hydraulic height of 290 feet, and a structural height of 330 feet. The dam boasts a massive storage capacity of 241,195 acre-feet, making it a crucial water resource for the region.
Managed by the Federal Energy Regulatory Commission, Alder serves multiple purposes beyond hydroelectric power generation, including recreation. With a surface area of 3,065 acres and a drainage area of 286 square miles, the dam plays a vital role in controlling water flow and providing flood protection. Its spillway, with a width of 128 feet, ensures controlled water release during peak flow events. Despite its high hazard potential, the dam's risk management measures are rated as very high, ensuring the safety and security of the surrounding communities. Overall, Alder stands as a testament to the intersection of water resource management and climate resilience in the Pacific Northwest.
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.
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Alder.
Boat launches
- Orville Road East 39200-41144, Eatonville
- 62nd Avenue Court East 39001, Eatonville
- State Game Road 11999, Pierce County
- Orville Road East 29517, Orting
- Spanaway Mckenna Highway Pierce County
- Skookumchuck Road Southeast Thurston County
Campgrounds
- Alder Lake - Tacoma Power
- Rocky Point - Alder Lake
- Brightwood Train Cars
- Sahara Creek Dnr Horse Camp
- Mount Rainier National Park Lodging
- Campground: Big Creek
Paddle runs
- Goat Rocks Wilderness Bounday To Cowlitz Falls Ferc Project Boundary In Ne1/4 Of Nw1/4 Of Sec 4, T11n, R6e
- Confluence With Ipsut Creek To Western Boundary Of Mount Rainier National Park
- Headwaters On The Nw Slope Of Mount Rainier At Carbon Glacier To Confluence With Ipsut Creek
- Headwaters In The Mystic Lake Basin On The North Side Of Mount Rainier To Northern Boundary Of Mount Rainier National Park
- Mount St. Helens National Volcanic Monument Boundary To Mount St. Helens National Volcanic Boundary In Sw 1/4 Of Sec 32, T11n, R5e
- Headwaters At The Terminus Of The Ingraham Glacier To Ends 1/4 Mile North Of Box Canyon
Track Alder 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 Alder
Where does the data for Alder 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 Alder.