Modesto Almond Farmer Banks Local Stormwater

Posted February 10th, 2016

Almond Farmer Nick BlomEast of San Francisco in the heart of the Central Valley, almond farmer Nick Blom is intentionally flooding 15 acres of almond trees in Modesto.  Researchers at the University of California, Davis are working with Almond Board of California and Sustainable Conservation to test if Blom’s orchard and other almond orchards can be sites for recharging groundwater aquifers.

As a member of the Board of Directors for the Modesto Irrigation District (MID), Blom’s hand quickly rose when he heard about the opportunity to experiment refilling the water basin during wet years.  The sandy soil on Blom’s farm allows water to easily trickle into the ground and down to the aquifers, which can benefit his crops as well as his community at large.

Not all Valley farms or crops are suitable for recharge, and that’s why the team is evaluating the risks and benefits of this practice by looking at the health of the almond tree and its roots - as well as water infiltration rates and water quality.  Alfalfa, grapes and pistachios were previously tested and have shown positive results without harming the plants or yields.

With water still on the ground in some areas from El Niño storms, some might question how the soil could absorb all that water.  In the beginning of January and again several weeks later, researchers flooded Blom’s orchard with about 6 inches of stormwater that infiltrated into the soil within 24 hours.  Now that’s a fast way to help refill a bank account.

Blom’s test orchard was modified with big berms - dirt mounded at the edges of the orchard- to hold the flooded water.  In order to measure the tree’s health after experiencing “wet feet” or roots from the flooded conditions, University of California, Davis researchers installed a variety of technology in the almond orchard.

An in-orchard rain gauge measures precipitation so the naturally occurring water plus the experimental flood water can be analyzed in tandem.  Several clear plastic tubes have been installed 3 feet into the soil to inspect the almond root zone.  The tubes are just large enough for a researcher to deploy a tiny video camera to examine the health of the roots.   There are also many soil sensors that measure the amount and movement of moisture in the soil.

Blom typically gets his irrigation water through MID from the Don Pedro Reservoir, specifically 3 to 3.5 acre-feet in a normal year.  However, this year he received just over one acre-foot from Don Pedro and had to make up the difference by pumping groundwater.  It’s another reason Blom feels recharging the aquifer for Central Valley residents, ecosystems and communities is so important.

Flooding almond orchards and California farmland has the potential to be an important part of California water management in the future.  Should the research prove the idea worthy of practical application, water managers could work with local farmers to dually recharge aquifers while managing excess water from heavy storm years – addressing two key problems in one way.

In tandem with this project, the Almond Board has funded research with Land IQ, the findings of which suggest that there are many more almond orchards suitable for recharge like Blom’s.  In fact 276,000 acres of almond orchards have been identified as having good or very good soil for recharge and nearly 400,000 acres are moderately good.  Leveraging almond acreage for groundwater recharge has the potential to benefit the entire Central Valley community. Once water is returned to the aquifer it serves the greater community, not just the farmer that used his land for that purpose.

While this research is seeking to prove the recharge principle in almonds, there are currently limitations related to infrastructure and policy. These challenges relate to moving the excess stormwater from where it currently flows to the fields where it can recharge aquifers – a question of canals and pipelines – and who has rights to winter stormwater.  Both of these questions are areas of focus for Sustainable Conservation who recently was invited to present initial findings to the California Water Commission.  The Water Commission is charged with allocating the $2.7 billion for water storage projects authorized by California voters through Proposition 1 in 2014.

Should this research prove successful, the California Almond community believes the vast amount of almond orchards suitable for groundwater recharge could play a key role in California’s sustainable water future.