U.S. Water News Online
BOISE, Idaho and SANTA CLARA, Calif.-- Water "banking" --
storing surplus water in regional aquifers for later use -- is
becoming more common as cities and states seek long-term solutions to
the perennial problem of ensuring adequate water supplies, especially
for periods of drought.
The Eastern Snake River plain aquifer in Idaho has just completed
its first full year under an aquifer recharge program managed by the
Idaho Water Resource Board.
Approximately 41,000 acre feet of water was recharged during Phase
Two of the program which started last September and ended April 1 of
this year. Another 139,000 acre feet was recharged in the 1995 Phase
One effort last spring.
And the Lower Snake River Aquifer Recharge District, based in
Hagerman, recharged upwards of 155,000 acre feet in 1995. Since 1986,
this district has returned more than 230,000 acre feet of water back
into the aquifer, according to district officials.
Meanwhile, the Santa Clara Valley Water District in California has
approved a water banking plan which calls for depositing surplus
water into the Semitropic Water Storage District bank for withdrawal
during times of drought. The agreement allows the district to store
up to 45,000 acre feet of State Water Project entitlements in
The agreement, which runs through the year 2035, enables the
district to hold onto imported water that otherwise would be lost
this year due to lack of local storage capacity. This agreement is
especially valuable in light of a potential shortage of up to 100,000
acre feet of annual water supply during future droughts.
Water delivered to the banking program is held in trust for the
district with Semitropic acting as trustee. To make a "deposit" or
"withdrawal," the district enters a point-of-delivery agreement with
the state Department of Water Resources and the Kern County Water
Agency to use the California Aqueduct to deliver water.
The district's cost per acre foot of water is estimated to be
$235, which compares favorably to the $225 per acre foot paid in 1991
for water from the state Drought Water Bank.
Aside from helping meet Santa Clara County residents' water needs
during times of drought, the agreement is also expected to help
restore and protect Semitropic's aquifer. While in the bank, the
water will be stored in Semitropic's groundwater basin. Farmers in
the Kern County district will use surface water in lieu of pumping
groundwater for irrigation.
The Semitropic Water Storage District has worked for more than 10
years to develop a groundwater banking program capable of storing 1
million acre feet. The banking program includes a groundwater
monitoring program with neighboring districts, surface water
distribution equipment, groundwater recharge facilities and pumps to
the California Aqueduct. Semitropic also conducts engineering and
When the banking and delivery agreements are finalized, the Santa
Clara Valley Water District will become Semitropic's second partner
in the program, joining the Metropolitan Water District of Southern
If Santa Clara Valley Water District does, as planned, deposit all 45,000 acre feet of water, it will own a 4 percent share of the banking program while Metropolitan, which banks up to 350,000 acre feet of storage, owns a 35 percent share. However, the Santa Clara district, according to officials there, continues to evaluate a greater level of long-term participation in the Semitropic water banking program.
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