Alder Dam is built on the Nisqually River and is located in Yelm, Washington. It was built in 1945 .
The dam is owned by the public utility, City of Tacoma.
Alder Dam is owned by the public utility, City of Tacoma.
|Dam length||1,487 feet|
|Dam height||285 feet|
|Structural height||330 feet|
|Hydraulic height||290 feet|
|Max discharge||80,000 cubic feet per second|
|Max storage||241,195 acre feet|
|Normal storage||214,500 acre feet|
|Surface area||3,065 acres|
|Drainage area||286 square miles|
Length of the dam is defined as the length along the top of the dam. This also includes the spillway, powerplant, navigation lock, fish pass, etc., where these form part of the length of the dam. If detached from the dam, these structures should not be included.
Height of the dam is defined as the vertical distance between the lowest point on the crest of the dam and the lowest point in the original streambed.
Structural height of the dam is defined as the vertical distance from the lowest point of the excavated foundation to the top of the dam. Top of dam refers to the parapet wall and not the crest.
Hydraulic height of the dam is defined as the vertical difference between the maximum design water level and the lowest point in the original streambed.
Number of cubic feet per second the spillway is capable of discharging when the reservoir is at its maximum designed water surface elevation.
Maximum storage is defined as the total storage space in a reservoir below the maximum attainable water surface elevation, including any surcharge storage.
Normal storage is defined as the total storage space in a reservoir below the normal retention level, including dead and inactive storage and excluding any flood control or surcharge storage. For normally dry flood control dams, the normal storage will be a zero value.
Surface area, in acres, of the impoundment at its normal retention level.
Drainage area of the dam, in square miles, which is defined as the area that drains to a particular point (in this case, the dam) on a river or stream.
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
An emergency action plan is defined as a plan of action to be taken to reduce the potential for property damage and loss of life in an area affected by a dam failure or large flood.
Inspections are every 1 ear.
|Distance to nearest town (miles)||18|
|NID ID (National ID)||WA00257|