C. Irrigation has severely reduced the flow of water in the Colorado River, making it an environmental issue. The river is a vital source of water for agriculture, industry, and households in the western United States, but overuse and mismanagement of water resources have led to significant environmental problems. The reduced flow of water has affected the river's ecosystem, including fish and wildlife habitats, and has caused the river to dry up before it reaches the sea. This has also led to conflicts over water rights and allocation among different states and stakeholders.