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.