Water District Drilling Wells for Reservoir Underground

Hydrologist Mark Wuttig spent Friday sitting in the middle of a citrus orchard near Moorpark studying the contents of 130 plastic Baggies bulging with assorted types of mud.

He had bags full of yellowish dirt, thick gray dirt and best of all--at least from the point of view of a hydrologist digging a well--bags full of loose, pebbly earth oozing with water.

A few feet from Wuttig, construction crews were drilling a rather unusual kind of well. Instead of getting water out of the earth, this well will be used to pump water back into the ground.

The well, which will be about 1,100 feet deep when finished, is part of a huge underground water storage project being built by Calleguas Municipal Water District, Ventura County’s largest water supplier. When the project is completed, a network of 30 wells will pump water into the Las Posas Basin, a vast aquifer that extends underground from Moorpark to the Oxnard Plain.

The purpose of the $50-million project is to store water for use in case of droughts or during emergency situations--such as an earthquake--when the main pipeline that carries state water into Ventura County might be damaged or destroyed.

“We can inject water easily and we can pull it out easily when it is needed,” said Calleguas planner Eric Bergh.

Calleguas receives water from Northern California through the Metropolitan Water District in Los Angeles. The water flows into Ventura County through an 8-foot-wide pipe in the Santa Susana Mountains and is sold to customers in Thousand Oaks, Camarillo, Oxnard, Simi Valley, Moorpark and some unincorporated areas of the county. About 500,000 people in the county get their water from Calleguas.

Bergh said the Metropolitan Water District is contributing about $47 million for the Las Posas Basin project.

When all the wells are built, Calleguas hopes to store up to 300,000 acre-feet in the aquifer, enough water to serve its Ventura County customers for three years. In terms of the overall size of Las Posas Basin--which geologists believe has a capacity of about 3.3 million acre-feet--the Calleguas contribution will be barely a drop in the bucket.

General Manager Don Kendall said using underground storage does less damage to the environment than building a reservoir. It is easier and less damaging than flooding a valley, and the water will be protected from external contaminants.

The underwater storage technology has been used in Ventura County before, but never to the extent that Calleguas is planning.

The reason Wuttig spent Friday judging the color, texture and geological origin of all those bags of dirt was to figure out the exact depth where the aquifer begins. Crews pull out a chunk of dirt every five feet in their digging and bring the sample to Wuttig to examine.

“It’s kind of like a big jigsaw puzzle,” Wuttig explained.

The pebbly stuff, extracted from about 600 feet below the surface, marks the beginning of the aquifer, which sounds a bit like a magical cavern full of water but is actually just a vast area of permeable soil. Water can move easily between the loose rocks and dirt.

When Wuttig establishes which spots are permeable, he and other hydrologists will make recommendations on where to put outlets, or screens, in the well. At each screen, water will be allowed to flow freely into the porous underground soil.

After the first four wells are built, they will be linked by pipes to a large Calleguas pipeline that runs parallel to California 118 and pumping will begin, possibly within a year. If each well were turned on and pumping water constantly, 365 days a year, they would inject about 2,500 acre-feet of water into the aquifer each year. Bergh said it is doubtful that they would be in constant operation, however.

Calleguas still needs to acquire several parcels of land in the Grimes Canyon area before it can begin work on the remaining 26 wells. Obtaining the grapefruit and orange orchard where the first well is being built was a considerable challenge.

The water district planned to condemn three acres owned by Joseph and Mary Viramontez to build the wells. But the couple filed a successful lawsuit against Calleguas, claiming the district had pushed the project through without an adequate environmental review. The case was eventually settled, with Calleguas agreeing to buy the whole 18-acre orchard.