Report shows drop in Nipomo Mesa groundwater levels

clambert@thetribunenews.comJune 20, 2013 

Nipomo residents are being asked to watch their water use carefully in response to a new report showing that groundwater elevations in one portion of an underground aquifer have declined.

A report prepared by a consultant for the Nipomo Community Services District shows that the groundwater underlying the western area of the Mesa was significantly lower this spring than the same time period last year.

The news is not totally unexpected, given the small amount of rain that fell over the Nipomo Mesa this past winter, said services district General Manager Michael LeBrun.

“It’s been a very dry winter, and therefore our groundwater basin didn’t recharge as much as hoped,” he said. “We do expect that it will drop and continue to drop through the fall.”

The evaluation was prepared by Brad Newton, a longtime district consultant. He reviews data from about 45 well measurements taken by several different agencies, including San Luis Obispo County’s public works department, over an area that extends outside the services district boundaries.

His report has not been reviewed by the Nipomo Mesa Management Area Technical Group, a committee established by a groundwater litigation settlement over water rights in the Santa Maria groundwater basin, which stretches from Santa Maria to Pismo Beach. The technical group takes measurements from eight wells.

The services district’s report comes as the agency is moving ahead with plans to build a pipeline to bring water to the community from Santa Maria.

District officials say the project is necessary to reduce over-pumping of the underground aquifer, which is the community’s only source of water.

On Thursday, the board voted unanimously to award about $17 million in contracts, including $14 million in construction contracts, for the first phase of the pipeline project. The project is expected to take 18 months to construct, with the first delivery of water to the area in late 2014.

The phased project is similar to a plan the district proposed last year, which stalled after Nipomo area property owners voted against plans to pay for it by raising property taxes.

Some local residents opposed to the project, including those who formed a group called Mesa Community Alliance, had argued the project pulls additional water from the groundwater basin that would flow to Nipomo naturally.

They also asserted that increased water usage has not affected the overall well levels, which have risen and fallen in conjunction with how much rainfall the area received.

The Nipomo services district’s report includes a chart that shows the ebb and flow of groundwater levels since 1975. It shows a significant drop in 1989, when parts of the county experienced drought conditions, and gradual improvements mixed with slumps.

If this winter brings abundant rains, it’s anticipated that next spring’s groundwater levels would show improvement, LeBrun said. Even so, demand on the basin has increased over the last 25 years, and that needs to be taken into account, he said.

“There is considerably more consumptive demand on the basin than in ’89,” he said. The biannual measurements “certainly do point out our reliance on weather patterns year-to-year and the impact that has on our sole source of water.”

Reach Cynthia Lambert at 781-7929. Stay updated by following @SouthCountyBeat on Twitter.

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