Twenty one irrigation districts in the Central Valley reported “conversion acres”. Conversion acres are those on which farmers used only groundwater for drip/micro irrigation although surface irrigation water was available.

The twenty one districts include about 2 million acres of irrigated area. Approximately 3.6% of that acreage (73,000 acres) has been “converted” to groundwater when farmers switched to drip/micro. Fourteen of these districts anticipate more conversion in the future. ITRC thinks that the conversion will be more rapid and greater than district personnel suspect.

The dominant factor that influences the conversion was the lack of flexible water delivery service to fields. Districts with rotation schedules had 3.5 times higher conversion rates than did district with 24 hour arranged deliveries. Districts with more flexible (than 24 hour arranged) deliveries did not report any conversion acres.

The conversion trend has been reversed by one district (Chowchilla WD) through a combined program that included district modernization and new pricing policies.

The extra energy required for groundwater pumping on the 73,000 conversion acres is estimated at 76,000,000 kW-hr/yr.


Bioresource and Agricultural Engineering

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