Answer:
For the development of navigation, flood control, irrigation, and hydropower
Step-by-step explanation:
The main reason dams and canals were built in Washington in the early 1900s was "for the development of navigation, flood control, irrigation, and hydropower."
This is evident in the fact that in 1925 when the US Congress approved the U.S. Army Corps of Engineers and the Federal Power Commission to jointly "...prepare and submit to Congress an estimate of the cost of making such examinations, surveys or other investigations... for efficient development of the potential water power, the control of floods and the needs of irrigation."
The report was eventually realized during the Franklin D. Roosevelt administration as the United States president