US Survey to determine if the Valley is sinking | ABC30 Fresno

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By ABC30

Thursday, September 24, 2009

Fresno, CA It looks as if an earthquake hit Three Rocks in western Fresno County. The gas station started sinking into the ground decades ago. Cracks have formed in the walls. Foundations have shifted.

Land once level has dramatically dropped here. National Resources Conservation Service Soil Scientist Kerry Arroues said, "That looks maybe like 10-15 feet and it's a lot more than that over much of this area and this is just one type of the subsidence."

The Three Rocks store next door also shifted because of hydro-compaction. It closed over a year ago but used to be a fun place to visit. Mike Strmiska of Fresno explained, "It's always been at a bit of an angle since I've been here. It kind of reminds you of the Winchester Mystery house or something."

You don't find level neighborhoods here. Even Highway 33 dips and dives along an uneven path. Arroues said, "As bad as this is, this is minor compared to the extent of the subsidence of this whole band of the west side."

Farmers are pumping full-time for every precious drop of water because of the drought and water delivery cutbacks. The US Geological Survey will use satellites to see if this area is sinking.

Sarge Green from the California Water Institute said, "When you extract groundwater too hard the material underneath loses its ability to support itself and it collapses."

A picture taken near Mendota shows the land dropped 30-feet between 1925 and 1977 because of excessive pumping. Kerry Arroues thinks it may have dipped 12-more feet since then. "I would say just this year it's gonna drop more than a foot in one year."

Of particular concern is the fear land is sagging under the California Aqueduct. Green said, "There is some local subsidence where shallower wells or the weight over the top near the surface could cause actual buckling or crunching of the aqueduct." That would cut off the water supply of millions in southern California.