As the US state of California faces its most severe drought in decades, one of its water agencies has clinched the prestigious Lee Kuan Yew Water Prize for its innovations to manage water.

The Orange County Water District will be awarded the sixth edition of the prize at this year's Singapore International Water Week in June, said Mr Chew Men Leong, chief executive of national water agency PUB, on Tuesday morning.

Mr Chew lauded the agency for its pioneering work in groundwater management and water reclamation using advanced technologies, its public outreach on water issues, and for advancing public acceptance of water reuse.

It was picked among 45 nominations from 24 countries.

Winners of the award receive $300,000, a certificate and a gold medallion.

The Orange County Water District manages a large underground aquifer that supplies about 70 per cent of the water for 2.4 million people in southern California. In 1976, it pioneered a programme using treated used water to prevent seawater intrusion at the groundwater basin's coastal edge, and in 2008 it began using reclaimed water to refill the basin, and also uses water from the Santa Ana River, storm flows, and imported water to do so.

"We see used water as a resource," said Orange County Water District general manager Michael Markus. "We need to get more than one use out of our water."