Valley Drought 2014: Causing Ground To Sink

You've heard of the big sinkholes in Florida and other places that swallow houses. The Valley doesn't have many sinkholes, but the ground in some areas is definitely sinking. It's an ongoing problem with new costs for everyone living here. As the ground drops, so do bridges, aqueducts and other structures, and it's starting to mean millions of dollars of taxpayer paid repairs.

KMPH News anchor Rich Rodriguez has been investigating what's called "subsidence" and he uncovers why farmers and the government are getting extremely worried over what's happening.

Farms need water, and in some parts of the Valley, that water is deep underground.

Subsidence occurs when deep well pumps take out too much of that water, and then the clay soil crumbles.

The problem had been held in check for decades, but now that growers are pumping water from hundreds of feet below the surface to keep their crops wet, some areas are sinking by as much as a foot a year.

One of the newest areas of subsidence is called Red Top. It gets the name from the Red Top Restaurant a couple miles away on Highway 152, about twenty miles east of Los Banos in Merced County.

In the past five years, deep well irrigation pumping has caused the ground to sink five feet.

Chris White with the Central California Irrigation District says the subsidence is being caused by the need for deep well pumps pulling water from beneath the Corcoran clay. "Corcoran clay is a major confining layer within this area. Confining in that the water underneath the Corcoran clay is under pressure the water under the Corcoran clay is not. If they over pump it, it reduces the pressure beneath the clay. As that pressure reduces, the clays are allowed to squeeze their water out and they compress," said White.

Subsidence isn't confined to just the west side of the Valley. NASA has been watching it by satellite for four years. A graph shows areas around Visalia dropped more than two feet in that time.

One of the more visual areas of subsidence is just south of the Westside community of Dos Palos, also in Merced County. A few years ago, a small boat could go under the bridge but today the water almost touches it.

Chris White says the land has subsided 10 to 12 feet since 1926 and is concerned about the bridge and how it's impacting the canal, that moves water about 65 miles to several hundred landowners. "It's not sinking uniformly; it's the middle of a 65 mile canal that's sinking. So we're creating a hole here that water can flow into the hole but it's having a difficult time flowing out of it," said White.

More than $4 million has been spent to raise the canal banks.

Subsidence began to resurface near the end of the first drought of the 21st century, around five years ago.

For years, farmers relied on canal water for irrigation. The canal winds thru the Sacramento-San Joaquin delta. Near Tracy, it must be pumped to begin heading south toward the Valley, the breadbasket of the world. But this year the preliminary water forecast is zero.

Westside farmer Shawn Coburn recently drilled a new 1200 foot well to keep his almonds and wine grapes alive, but he says it's only a temporary band aid. "We can't rely on groundwater. The projects were built to provide surface water for irrigated lands to stop the overdraft of groundwater that was occurring back in the 40's and 50's. That's what the projects were built for. Now the projects are basically idled due to the pumping restrictions," said Coburn.

Coburn farms on the Westside near Interstate 5 and says there are no signs of subsidence. The U.S. Geological Survey is concerned about the ground sinking. In its report from last November, it warned that large-scale subsidence has the potential to cause serious damage to water delivery canals. Those canals bring water more than 100 miles to the Valley where it feeds thirsty crops and cities. U.S.G.S. says subsidence may cause big problems that need to be overcome to ensure reliable water delivery.

Back at Red Top, steps are being taken to halt the ground from turning the area into a big crater.

The Central California Irrigation District is helping even though it serves growers miles and miles away. "The resources in this area, the landowner base that is very motivated to get something done that we can put together a solution to subsidence in this specific area," said Chris White.

White says the solution, is to recharge the shallow water table by flooding the area when it rains. Growers will then re-drill their wells to tap the shallow aquifer. Despite non-stop well drilling across the Valley, farmer Shawn Coburn doesn't believe the state will create new regulations. "I think you have to manage groundwater basin by basin; it's not a statewide issue that one law fits all because different water basins have different characteristics. I think you're going to run into a pretty big fight as far as trying to manage ground water on people's personal property."

It's going to take more than $2 million to raise the bridge south of Dos Palos, and that could be just a drop in the bucket when it comes to future problems.

The U.S.G.S. study discovered that subsidence is reducing the capacity of the California aqueduct. It stretches for more than 700 miles. It also warns that with the uncertainty of surface water the potential for future subsidence remains high.

There have been state and federal water projects that were supposed to stop subsidence but farmers say they haven't been managed well, so they aren't working.

In case you think a dropping water table and less water coming down the canals doesn't affect you, experts say look for 20,000 lost jobs this year, a $7.5 billion hit to the ag economy in California.

And because of that, you'll pay much higher prices for your groceries.