By John Lindt,Visalia Times-Delta
The canal that helps bring food to tables across the world has a big problem — it’s sinking.
Land subsidence along the Friant-Kern Canal in Tulare and Kern counties has increased in the past five years, according to Dan Vink, South Valley Water Authority executive director.
The sinking terrain, reported to be two to three feet — mostly along a 25-mile stretch, has already reduced the capacity of the key irrigation artery by 50 to 60 percent in some locations.
“It’s like a big dip, a bowl or depression in the land that has the effect of not allowing flows to the south,” Vink said. “The Bureau of Reclamation knows about it and estimates are it could be a $200 to $500 million problem.”
Reported stolen vehicle recovered from Friant Kern Canal north of Exeter. Luis Hernandez
Even if they had “that kind of money” and they hurry “it could take five years or longer to repair,” he added.
“Land subsidence, and especially impacts of that subsidence to the Friant-Kern Canal are a serious threat to the delivery of water supplies to farms and rural communities that rely on the canal for water deliveries,” said Tricia Stever Blattler, executive director, Tulare County Farm Bureau.” It is a very important issue for the Bureau of Reclamation to address sooner than later.
Blattler said time is of the essence.
“Fixing the subsidence problems are only going to be more expensive and more dire the longer the Valley goes without proper maintenance, upkeep, and the ability to recharge the groundwater aquifer,” she said. “Every year that environmental constraints reduce the amount of water flowing into our groundwater aquifer, the worse subsidence becomes, and the harder it will be to reverse it.”
The canal is designed to carry 3,500 cubic-feet per second but flows have been restricted to 1,700 cubic-feet in places such as Deer Creek and Earlimart areas. Districts farther south are also dealing with the reduced flow.
The impact on farmers mimics a drought — not enough water available when they need it.
“Many of our growers rely on surface water deliveries from the Friant water system, as well as municipalities,” said Marilyn Kinoshita , Tulare County’s ag commissioner.
What is a farmer to do? Go back to pumping groundwater, Vink said.
However, it was vigorous pumping that has been blamed for land subsidence in the first place — both here and on the westside of the Valley, impacting the critical California Aqueduct, as well.
NASA mapped land subsidence and reported the rate has gotten a lot faster in the recent drought with a huge bowl seen in the Corcoran area.
Likewise, in the Dos Palos area, USGS measured a drop of nearly five feet from 1988 to 2013 effecting the Delta Mendota District.
Repairs to restore the capacity on the 126-mile Friant-Kern have been carried out several times over the years with the banks of the big canal raised in some places by six feet.
The canal irrigates about a million acres.