The San Diego County Water Authority has completed a major rehabilitation project on the historic First Aqueduct in North San Diego County, it was announced Thursday.

The project renovated and replaced dozens of structures on two large-diameter pipelines which delivered the first imported water to the San Diego region in 1947 and remains a part of the regional water delivery system. The construction contract for the project was worth approximately $30 million.

“The First Aqueduct delivered imported water to our region for the first time more than 70 years ago, and it remains critical to water supply reliability for our region to this day,” said Gary Croucher, chair of the authority’s board of directors. “Coordination across water authority departments and collaboration with our member agencies allowed us to complete this extraordinarily complex project and ensure these pipelines operate for generations to come.”