A new water pump station is being constructed in Moorpark that water district officials say will bring water to the area in the event supplies are cut during emergencies.

The Calleguas Municipal Water District and the Metropolitan Water District of Southern California are constructing the pump station on 1.8 acres on the east side of Spring Road, south of Arroyo Simi. The station is expected to be completed around December 2008.

The station is part of the $80 million Las Posas Aquifer Storage project, also shared by Calleguas and Metropolitan water districts.

Eric Bergh, spokesman for Calleguas, said the storage project is expected to bring a reliable source of water to residents of Ventura County if imported supplies are limited because of scheduled maintenance shutdowns, drought, earthquakes, levee failures or other emergencies.

Bergh said an estimated 600,000 residents who receive water through the Calleguas water district will benefit from the project.

"It's an extremely significant project," Bergh said. "Right now, there's a single source bringing water into this area, so a backup plan is really needed."

The pump station will consist of a two-story structure and tower. Water district officials and Moorpark city planners have met over several years to make sure the structure fits in with the surrounding neighborhood, Bergh said.

The storage project will allow the pump station to draw pre-treated water stored at the Las Posas Groundwater Basin, an aquifer 18 miles long, 4.5 miles wide and almost 1,500 feet underground along Grimes Canyon Road near Moorpark.

After leaving the aquifer, the water will travel through wells connected to a water pipeline that was placed under Los Angeles Avenue several years ago. It will be distributed to residents after being treated once again with chlorine.

During especially rainy years, excess water is injected back into the aquifer and banked until needed.

The aquifer currently stores 80,000 acre-feet of surplus water, but will eventually store 300,000 acre-feet once the project is completed, Bergh said. The station will be able to pump 70,000 acre-feet of water per year, with one acre-foot able to supply two families with water for a year.

The existing water supply to the area is provided by a system of reservoirs, aqueducts and pumping facilities that bring water from Sacramento's San Joaquin Delta in Northern California to Southern California.

Bergh said Lake Bard, between Simi Valley and Thousand Oaks, also stores surplus water, but it is too small to provide enough in an emergency.

Twenty years ago, Calleguas officials started looking for alternative ways to store water because of ongoing drought and lack of available land in the area, Bergh said.

Water industry officials and environmental organizations have supported underground water supplies because they don't take up land, no water is lost through evaporation, and the water is protected from contaminants.

Underground storage also raises the groundwater level, requiring less energy to pump water out of the ground by the water district and nearby well owners.