Water plays a significant role in the politics of California, an arid state with the country’s second largest city, a population of 30 million people, and a massive agriculture industry. The greatly increased availability of water during the Great Depression, owing to the construction of the Hoover Dam and rerouting of the Colorado River, was a significant factor in the expansion of Southern California; today it provides approximately 60 percent of that region’s water. While the state has significant subterranean ground water, not all is usable and the cost of obtaining it from deep underground often proves prohibitive.
A fundamental divide exists between business interests and environmentalists. Those who favor economic development also frequently support expanded personal use, while those concerned about long-term environmental impact advocate stricter conservation measures. In the northern part of the state, which is mountainous, much of the water comes from snowmelt runoff. Some of the controversies relate to proposals to divert water to the southern part of the state, which chronically has a greater need. Environmental factors are one of the leading causes mentioned in preventing such diversion projects from being developed.
A key case in which water diversion caused serious environmental damage is often called the “California Water Wars” of the 1910s–1920s. In order to expand the amount of water for its residents and businesses, the city of Los Angeles purchased three hundred thousand acres of land and the attached water rights from Owens Valley. The water was moved via a massive aqueduct. Both the land purchases and the aqueduct construction were accomplished partly through corrupt and illegal means, including land purchases by the mayor of Los Angeles.
Having this water greatly benefited Los Angeles; meanwhile, Owens Lake was completely dried up, and the lack of water rendered Owens Valley a dustbowl. Much of the water went to the San Fernando Valley for agricultural use, and conflicts escalated into attacks such as dynamiting the aqueduct.
These issues continued into the 1990s. In the 1940s, a related project was carried out with Mono Lake, just north of Owens Valley. One documented problem was disturbing the natural habitat for migratory birds. In the 1970s–1990s, lawsuits on behalf of Mono Lake ended the diversion.
The central hub through which water moves is the Delta east of San Francisco Bay. Under former Governor Jerry Brown, a project was proposed to build a tunnel through which water would be taken from the Sacramento River further upstream. Current governor Gavin Newsom has abandoned that plan. During his administration in early 2020 the state developed the California Water Resilience Portfolio.