The province known as a major hydropower province in the United States is Washington. This region boasts an extensive network of dams and hydroelectric power plants that generate a significant portion of the state's electricity. The primary reason for Washington's prominence in hydropower is its abundant water resources, particularly the Columbia River, which flows through the state and provides a substantial source of hydroelectric power.

Washington's hydropower sector is supported by several factors. Firstly, the state has a long history of investing in hydropower infrastructure. The first hydroelectric plant in the United States was built in Washington in 1895, and since then, the state has continued to expand its hydropower capacity. According to the U.S. Energy Information Administration, as of 2020, Washington had over 30 hydropower plants, generating approximately 54% of the state's electricity.

The Columbia River, which spans both Washington and Oregon, is a key contributor to this hydropower success. The river's flow is managed by the Columbia River Treaty, a joint agreement between the United States and Canada. This treaty has facilitated the construction of numerous dams and reservoirs that have significantly increased the region's hydropower potential. The Grand Coulee Dam, located in Washington, is one of the largest hydropower plants in the country, with a generating capacity of over 6,800 megawatts.

Additionally, Washington's hydropower plants are highly efficient and environmentally friendly. They produce electricity with a low carbon footprint, making them a crucial component of the state's commitment to reducing greenhouse gas emissions. According to the Washington State Department of Ecology, hydropower is the state's largest source of renewable energy, and it is expected to remain so for the foreseeable future.

In conclusion, Washington is known as a major hydropower province due to its abundant water resources, extensive infrastructure, and commitment to renewable energy. The state's hydropower sector is a testament to the potential of hydroelectric power in the United States and its role in providing clean, reliable energy.