Valley can expect heavy rain amid climate change. Irrigation district aims to capture some
The Turlock Irrigation District will help test a new approach to recharging the groundwater underneath farmland.
The trial will take place at an almond orchard in the Ballico area of Merced County. TID will wait for good-size rainstorms, hopefully as soon as this autumn, and divert the runoff to the farm via a canal idled at the end of irrigation season.
The project is one of several aimed at boosting Central Valley aquifers, overseen by the California Department of Water Resources.
TID is partnering on the project with Sustainable Conservation, a nonprofit that works with farms and other businesses around the state. It is based in San Francisco and has a branch office in Modesto.
“Recharge has a great potential to help buffer the effects of drought,” said Aysha Massell, a program director for the group, during a Zoom briefing for the TID board Tuesday. “It can’t solve everything in our groundwater overdraft problem, but it’s definitely a very important tool in our tool belt.”
Recharge already in wet years
The project is tiny compared with recharge already accomplished in wet years by TID and other suppliers. The Turlock district has long offered an extra delivery at the end of irrigation season in such years, hoping to bolster aquifers that could be tapped during drier times. Recharge also happens in floodplains that have been restored along rivers in recent decades.
The Ballico project is a more surgical approach, aimed at a groundwater zone near TID’s eastern border, where pumping has long exceeded recharge.
The site was chosen also because of its sandy soil, which lets water pass easier than other types, said Wes Miller, supervising engineering technician for the district.
TID will have nominal costs, including pumping water from the canal to the orchard and monitoring the level of a farmer-owned well at the site. The canal normally is used in the off-season to divert storm runoff to the Merced River.
The project is based on the idea that climate change will bring longer droughts punctuated by intense rain storms. It also could mean much less of the Sierra Nevada snowpack supplying Don Pedro Reservoir, the main storage for TID and the Modesto Irrigation District.
Will it damage nut trees?
The study will look at possible damage to the almond trees from the intentional flooding. Orchards usually get just local rainfall from fall to early spring, and then are irrigated from canals and wells. The researchers also will see whether the aquifer is tainted by pesticides, nitrates and other substances in the orchard soil.
These concerns were found to be unwarranted in a similar project launched by MID in 2016, said Daniel Mountjoy, director of resource stewardship for Sustainable Conservation. The district delivered excess storm runoff to a Maze Boulevard almond orchard, an effort also involving UC Davis, the Almond Board of California and other partners.
TID board chairman Michael Frantz co-owns a Hickman nursery that grows plants for garden centers, and also is a board member for Sustainable Conservation. The group has worked on dairy manure handling, wildlife habitat, toxic chemicals and other efforts.
“It’s been fun to watch Sustainable Conservation come alongside and learn from farmers,” Frantz said Tuesday, “and I think there’s room for us to learn as well.”
This story was originally published October 28, 2022 at 8:00 AM.
