California water wars: A century of wrangling over Los Angeles’s water

Just before midnight on March 7, 1928, the St Francis Dam, located roughly 80km (50 miles) inland of Los Angeles, collapsed. There were no witnesses to the disaster – or none who survived – but investigators later determined that the 56-metre-tall (184ft-) barrier fell all at once, sending 12.4 billion gallons of water surging down the San Francisquito Canyon in a wave 43 metres (141ft) high.

Five hours later, the waters finally dumped into the Pacific Ocean, leaving chunks of concrete in their wake as heavy as 10,000 tonnes. By then, the gush of water was nearly 3km (2 miles) wide, laying waste to several towns along the way, cutting power throughout the region, and ultimately killing at least 431 people, many of whom were washed out to sea, their remains found as late as 1994 and as far as the Mexican border.The dam had been marred by cracks and leaks ever since its reservoir began filling with water in 1926, but its builders deemed such issues inconsequential and continued to fill as planned. The water it contained – extracted amid much contention from Owens Valley, a lush oasis in a desert region between the Sierra Nevada and White Mountains some 320km (200 miles) to the north – was needed to provide for Los Angeles’s rapidly growing population.Over the next two years, new cracks formed and seepage became increasingly apparent around the abutments where the dam met the sides of San Francisquito Canyon. By February 1928, large leaks were releasing so much water that farmers in the area began to worry. Again, the dam’s chief engineer – William Mulholland – declared it was normal.

On the morning of its collapse, Mulholland and his colleagues had conducted a thorough inspection of the dam, determining even then that it was safe but in need of future repairs. Hours later, the waters burst through it. An investigation would later conclude the breach was due to “defective foundations”.

It was the largest American civil engineering disaster of the century – a byproduct of western expansion and the struggle known as the California Water Wars, which pitted the public against private business interests and set the stage for a century of conflict over the state’s most contested resource.‘We are going to turn that country dry’
Water is still a major issue for California nearly 100 years later. During the fires that ravaged Los Angeles in January 2025, firefighters’ ability to battle the blazes was hampered by low hydrant water pressure. Investigators said this was caused by unusually high demand driven by firefighting efforts, while then-President-elect Donald Trump blamed state Governor Gavin Newsom, claiming the water shortage was due to “overregulation” – referring mostly to regulations designed to protect endangered species in the surrounding areas.