How do dams and water withdrawals affect the Colorado River delta?

The extensive construction of dams and the heavy withdrawal of water for agricultural, municipal, and industrial use have left the Colorado River severely over-apportioned. By the time the river reaches its delta at the Gulf of California, it is reduced to a mere trickle and, at times, runs completely dry.1

This depletion is the result of the river’s water being used multiple times upstream by farmers, urban dwellers, and ranchers. The lack of consistent flow has radically disrupted native habitats and species in the basin. To mitigate these impacts, the U.S. Department of the Interior has experimented with releasing large flows from dams during the spring to mimic natural floods, which helps redistribute sediment and flush out contaminants. However, the river remains a subject of intense controversy, with some experts even considering the removal of dams to improve the river's flow.12