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LA GRANDE

RESERVOIR LEVELS
Rock Dam Nisqually River
May 11, 2025


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La Grande is a captivating hydroelectric dam located in Yelm, Washington, along the scenic Nisqually River. Completed in 1944, this concrete structure stands at an impressive height of 192 feet, with a total hydraulic height of 210 feet. The dam boasts a storage capacity of 7,200 acre-feet and serves as a vital source of renewable energy in the region.

Managed by the Federal Energy Regulatory Commission, La Grande plays a crucial role in regulating water flow and generating hydroelectric power for the surrounding area. With a maximum discharge capacity of 88,000 cubic feet per second and a controlled spillway width of 128 feet, the dam is designed to withstand high hazard potential. Despite its age, La Grande remains a key player in water resource management and climate resilience efforts in Thurston County, Washington.

As a significant landmark in the region, La Grande's risk assessment ranks at a very high level, highlighting the importance of ongoing monitoring and maintenance. While the dam's condition assessment is currently not available, emergency action plans are in place to ensure the safety of nearby communities in case of unforeseen events. With its rich history and impressive engineering, La Grande stands as a testament to the intersection of water resource management, renewable energy generation, and climate adaptation in the Pacific Northwest.

Year_Completed 1944
Dam_Height 192
River_Or_Stream Nisqually River
Dam_Length 710
Primary_Dam_Type Concrete
Surface_Area 450
Hydraulic_Height 210
Drainage_Area 292
Nid_Storage 7200
Structural_Height 217
Outlet_Gates Tainter (radial) - 4
Hazard_Potential High
Foundations Rock
Nid_Height 217
       

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