California Walnut Sustainable Water Management Session
How Growers Are Adapting Their Water Management Strategies
Water continues to be one of the most significant challenges that California walnut growers face. Changing weather patterns and evolving regulations can affect water availability from year to year, requiring growers to adapt while maintaining yield, quality, and profitability.
To explore how walnut growers are adapting, the California Walnut Commission and Measure to Improve recently hosted a Sustainable Water Management Session featuring walnut growers Jason Colombini (Jay Colombini Ranch Inc.) and Josh Barton (Gold River Orchards), along with soil and agriculture scientist Stephanie Tillman (Land IQ). This session focused on how technology can support irrigation decision making, practical approaches growers are using today, and how evolving water regulations may shape the future of walnut production.
Using Technology to Support Better Irrigation Decisions
Both growers emphasized the importance of appropriate irrigation to ensure crop quality and orchard health. While underwatering is a key concern with changing regulatory requirements, overwatering can increase pest pressures in the field. Finding a balance is a challenge for many growers.
Josh outlined the layered approach Gold River Orchards uses to monitor both soil and tree conditions. Rather than relying a single measurement, they use multiple tools to better understand and support irrigation decisions, including:
Soil moisture monitoring systems
In-field pressure sensors
Tensiometers
Soil tubes for field verification
Stem water potential measurements using pressure bombs
Aerial imagery and remote sensing technologies
Evapotranspiration (ET) data and weather monitoring
“We take both a soil approach and a tree approach” - Josh Barton, Gold River Orchards
All presenters emphasized that technology does not replace field observations, it complements it. It provides additional context that helps improve confidence and decision-making. As new tools become more accessible, growers are increasingly able to move from reactive irrigation management toward more proactive strategies.
The session also highlighted how advances in agricultural data and spatial analysis are creating new opportunities for water management. Stephanie Tillman of Land IQ shared how remote sensing, evapotranspiration modeling, groundwater data, and land-use mapping are helping growers, water agencies, and regulators better understand water use at both field and regional scales.
LandIQ's work demonstrates how combining satellite imagery, field observations, and advanced analytics can improve decision-making and support long-term water planning. These tools are becoming increasingly important as growers seek to understand water supply reliability, identify opportunities for groundwater recharge, and make more informed management decisions under changing conditions.
"The reason we track regulations like Sustainable Groundwater Management Act (SGMA) is because it informs us about what kinds of spatial data are needed in the industry and why they're important to people managing resources." - Stephanie Tillman, Land IQ
Practical Approaches to Irrigation Management
Irrigation Management is much more than deciding how much water to apply; other field management decisions in-field can have cascading effects on irrigation.
Jason of Jay Colombini Ranch shared that he has begun integrating a Brassica cover crop on every other row in his orchards. This strategy has been incredibly successful in his operation and has led to improved water infiltration in-field and soil health; that has in turn improved his irrigation efficiency.
Jason also referenced the implementation of split irrigation on his orchards. Split irrigation involves never irrigating for more than 24 hours at a time and allowing at least 24 hours between sets. This practice helps to control Phytophthora populations in the field and promotes a healthier crop by providing a cooling mechanism during intense heat events. This aligns with UC IPM guidance, which notes that “periods of 24 hours or more of saturated soil favor Phytophthora infections.” (UC IPM)
“Once we switched that block over to weekly 24-hour sets, tree death has gone down and production has gone up” - Jason Colombini, Jay Colombini Ranch Inc.
Looking to the Future
Much of the discussion during the session addressed implementation of California's Sustainable Groundwater Management Act (SGMA) and what it could mean for long-term agricultural water availability.
Growers acknowledged that groundwater sustainability requirements will likely shape future production decisions throughout walnut-growing regions. As groundwater allocations and pumping restrictions evolve, producers need to rethink irrigation strategies, improve efficiency, and evaluate how different cropping systems align with available water supplies.
“We recognize that for many growers, the challenge is no longer simply how to irrigate efficiently today, but how to remain productive and profitable under future water constraints. Decisions made today lay the groundwork for the future."- Gabe Worthington, Measure to Improve LLC
This Sustainable Water Management Session highlighted the innovation and expertise already driving progress across the California walnut industry. While the path forward may look different across regions and operations, proactive water management will be critical to the long-term success of California walnut production.
Conversations like this continue to foster collaboration and knowledge within the industry, helping growers to navigate the future of water management.