By
Rick Elkins
Visalia - The depth of water underneath the city of Visalia has fallen to its lowest level in history.
Phil Mirwald, manager of California Water Service, said water levels in Cal Water's wells now average 115 feet, down another 8 feet from last summer. The latest measurements were taken in June.
“Although the water table has dropped, operationally it has not affected us,” said Mirwald of the fact Cal Water has not had any wells go dry or had to make any major adjustments this summer.
Mirwald said the depth of the water underneath the city continues to drop even though the city of Visalia and Kaweah Delta Water Conservation District have taken major steps to recharge the underground water basin.
This summer, the city purchased water and ran it down several creeks in the city, one of the most effective ways to seep water into the underground system, said Mark Larsen, general manager of KDWCD. (See related story on Larsen and Bruce George on page 17 -- second front page.)
More than six years of below-average rainfall is taking its toll on the groundwater supply, not only in Visalia but throughout the Valley. Water officials say the best way to recharge the underground water supply is first, not pumping water from it, and second, having surface water or irrigation water that does seep down.
Since February of 2008, the water table has dropped 15 feet (from 100 feet to 115). However, the water table dropped just 2 feet between February and June, compared to a 7-foot drop during the same period last year.
The city of Visalia, and many others such as Tulare, gets all its domestic water from the underground. Mirwald said Visalians used 48 billion gallons of water during the month of August, an astronomical sounding amount. That was a little more than what was pumped in August of last year. The city uses about 200,000 acre feet of water a year, said George, former manager of KDWCD.
Mirwald and Larsen agreed that water recharge is getting a lot more attention these days. “We don't have surface water available so we have to be good stewards of our groundwater,” said Mirwald.
Larsen said the Kaweah basin “is in a state of overdraft” and they expect the underground water table to drop further. He said as the supply dwindles, the drop gets more dramatic. On average, said Mirwald, the water level under Visalia has been dropping about a half of a foot a year.
Recharge is Important
What is needed, he said, is a wet
year and some climatologists are suggesting that an El Nino condition
might exist, spurring hopes of a wet year. Those wet years serve to not
only reduce the need to pump as much water, but also provide surface water.
“In wet years, you have farmers using surface water,” said
Larsen.
Wet years usually provide enough water to put water in recharge basins and both Visalia and Tulare have been working to develop more basins. Both cities have ordinances that include water recharge basin development fees.
Larsen explained that part of the reason the water district was formed in 1927 was to protect the underground water supply. However, growth in both agriculture and residences has slowly cut into the underground supply.
He said there are 4,000 acres of recharge basins in the district, half of that developed before 1950.
But, in the last five years, he said, “cities have really focused on or understood the principal of recharge – that water comes from the underground.”
He said there are four main sources of water recharge. About a third comes from water running down stream and river channels, a third from ag flood irrigation, 15 percent from heavy rain and 11 percent from recharge basins.
Even a wet year will not have immediate
impact, with Mirwald saying it takes several years for the water table
to recover. However, it would slow the overdraft.
Using Effluent Water
On Tuesday, the Visalia City Council got a report from Provost and Prichard's engineering of how it can use effluent water from the city's wastewater treatment plant to both reduce underground pumping and to exchange that water for cleaner water.
The recommendation is to use water from the wastewater plant, located west of Highway 99, to water Plaza Park, Valley Oaks Golf Course and agricultural areas near the airport.
According to the report, the plant discharges over 14,000 acre feet of water annually.
It is recommended the city upgrade is treatment of the effluent that would make it unrestricted in its use. Right now, the water can only be used on fodder and fiber crops such as alfalfa, silage, corn and cotton. The upgraded treatment would not allow the water to be used for domestic drinking, however.
By utilizing the water, the city can save approximately 3.2 million gallons a day of groundwater at the golf course alone.
The water exchange with the Tulare Irrigation District would allow the city to discharge some of its treated effluent into a TID ditch to be sold to its users or be used for underground recharge. In turn, the city would receive a proportional allotment of water upstream to be used for underground recharge.
The one potential stumbling block is the proposal would cost approximately $6 million.
Cal Water Upgrades
Mirwald said Cal Water continues to aggressively install as many domestic water meters as possible.
“It's going well,” he said, adding that they are now about halfway to installing all the meters. The goal is to be finished by 2012.
“It will be interesting to see
how that affects water usage,” he said.
Work is also near completion on the system's million-gallon water tanks
being installed along Riggin Avenue.
“The one at Roeben and Riggin should be online around the first of January,” he said, with the second tank west of Road 76 expected to be completed by the middle of next year.
The tanks are completed. Workers are now constructing the boosters and buildings at the sites.
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