SAN DIEGO - The $568 million project to double the capacity of the San Vicente Reservoir in Lakeside has reached a major milestone.

The San Vicente Dam now stands 337 feet tall, which means it can hold twice as much water as it did before.

"It's critical. We live in a desert and we're at the end of a very rusty pipe and a river that's drying up. So we need a water supply in San Diego to keep this billion-dollar economy going," said Thomas Wornham with the San Diego County Water Authority.

The County Water Authority said the extra storage will mean San Diegans will have a safety net in case an earthquake or attack cuts off the water supply.

Construction on the San Vicente Dam, which has been going on for 24 hours a day, seven days a week for the past several years, is expected to be completed by next year.