Groundwater: out of sight but not out of mind

Vicky Boyd

Vicky Boyd,
Editor

Buried deep below the soil surface, groundwater may be out of sight. Increasingly, though, the natural resource is anything but out of mind.

Several efforts, both voluntary and regulatory, are ongoing to try to reduce groundwater overdraft and increase recharge. How these will affect agriculture remains to be seen and may not be known for years to come.

Arkansas completed a revised water plan in 2015 designed to guide the state through 2050. Among its findings: The state is predicted to have an annual groundwater overdraft of 7 million acre-feet. To address that, the state will need to convert more irrigated acres to surface supplies from groundwater. Then the question is: How do you finance these surface supply projects?
Mississippi also continues to grapple with overdraft of the Mississippi River Valley Alluvial Aquifer, which supplies much of its irrigated agriculture. A multi-state effort is currently examining recharge options.

Nowhere is the challenge as prominent as in the Golden State. The Sustainable Groundwater Management Act, signed in 2014 by then-Gov. Jerry Brown, requires groundwater agencies to develop plans that would balance extraction with recharge by 2040 or 2042. An environmental impact report tied to SGMA downplayed its effect on agriculture, saying many growers would simply turn to surface water.

But the authors of the groundwater plan didn’t factor in proposed unimpaired flows, where water diversions could be cut by up to 45% on the Sacramento River and its tributaries. The Sacramento River is a major water source for Northern California rice production.

All of this boils down to trying to obtain “more crop per drop,” or as a recent Rabo AgriFinance report put it, “more profit per drop.”

The report’s author, senior analyst Roland Fumasi, credits rising water scarcity and cost for driving California’s increased permanent crop plantings — particularly almonds. Many rice producers in the Sacramento Valley have turned to tree nuts, where soil conditions allow, because of increased returns per acre.

Even if growers don’t have rice alternatives, researchers like University of Arkansas’ Chris Henry are trying to raise awareness of water conservation. Through the university’s “Most Crop Per Drop Contest,” participants are challenged to grow a high yield with less water.

The 2019 season was an anomaly because of unusually wet conditions. That said, winner John Allen McGraw of Lincoln County, Arkansas, grew 208 bushels of rice per acre for a water-use efficiency of 7.2 bushels per acre-inch. Second-place winner Joey Massey grew 210 bushels per acre for a water-use efficiency of 4.9 bushels per acre-inch, and that was with row rice.

Read more about the winners managed their water beginning on page 16.