New map shows plunge in Paso Robles groundwater levels

dsneed@thetribunenews.comAugust 15, 2013 

A new map of the Paso Robles groundwater basin shows that aquifer levels in the basin have dropped dramatically in the last four years — meaning that most of the basin has now suffered water drops of at least 70 feet or more since 1997.

The previous map, using data from 1997 to 2009, found that the most severe declines of 70 feet or more were concentrated in a circular area east of Paso Robles often referred to as the bull’s eye or cone of depression.

The San Luis Obispo County Department of Public Works published the map late Wednesday in preparation for a meeting Thursday of the basin’s blue ribbon management committee where the maps were briefly discussed.

In the past four years, the bull’s eye has expanded north and south to include the Creston area and the South Gabilian area north east of Paso Robles. Groundwater declines have also worsened in the San Miguel and Shandon areas.

The map also shows a new area of significant groundwater decline in the San Juan area, a sparsely populated area north of Highway 58 and west of San Juan Creek.

The new depression in the San Juan area is probably due to a combination of agricultural pumping and the recent drought, according to Courtney Howard, water resources engineer with the county. That area, along with the Atascadero sub-basin, tends to refill more quickly with rainwater, she said. It also has a vineyard and irrigated pastureland.

The two county supervisors whose districts include the basin, Frank Mecham and Debbie Arnold, reacted cautiously to the maps Thursday. They acknowledged that the maps show a significant change but wanted more time to evaluate them and the data that went into them.

“I’m going over them right now,” Arnold said. “I want all the facts.”

The maps could significantly affect a meeting supervisors will hold Aug. 27 to consider, among other actions, adopting emergency ordinances to limit groundwater pumping in the basin. One option they said they wanted to look at is to limit an emergency ordinance to the bull’s eye area.

However, the bull’s eye no longer exists on the new map. It has expanded to a much larger, amorphous area.

Howard said she was not particularly surprised by the new map. Hydrological monitoring of the basin has shown consistent declines in the water levels in recent years, including years with normal rainfall levels, she said

At Thursday’s meeting of the blue ribbon committee, Chairman Larry Werner was critical of the fact that the map was released the evening before the meeting and did not include any analysis of its significance.

“That was not a good move,” he said. “We are going to need a little time to digest the information.”

Joy Fitzhugh with the San Luis Obispo County Farm Bureau Federation pointed out that three of the four years reflected in the new map have been drought years and that could have influenced the changes.

Others reaffirmed their argument that the basin is facing a severe crisis and urgent action must be taken to restrict new vineyards’ plantings and other steps to protect hundreds of rural homeowners who are in danger of having their wells go dry.

“The change in the last four years is shocking,” said Jan Seals, treasurer for PRO Water Equity, a group advocating emergency pumping restrictions, who spoke during public comment. “People need immediate help. This crisis is real, there is no question.”

Wine & Water: For more about the Paso Robles groundwater crisis, read our investigative report: http://www.sanluisobispo.com/wine-and-water/

A look at the basin

These maps provided by the San Luis Obispo County Department of Public Works show how aquifer levels in the Paso Robles groundwater basin have dropped. The first map shows the change in groundwater elevation from 1997 to 2013; the second shows the change from 1997 to 2009.

Change in Paso Robles groundwater basin elevation

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