Water & Irrigation

California droughts are becoming more frequent and persistent, as warmer winter temperatures driven by climate change reduce water held in the Sierra Nevada snowpack and result in drier soil conditions. To increase our resilience to future droughts, Californians must use water more wisely and efficiently.

​Groundwater Sustainability Plan

​The Groundwater Sustainability Plan is a basin wide plan that lays out a path for sustainable management of a groundwater basin over a 20-year period, and focuses on avoiding undesirable results. It was designed to keep groundwater resources at or above 2015 levels.

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Irrigation Assessment

​Farming is the largest consumer of water in Napa County. We have partnered with Napa RCD to share ways growers can irrigate more efficiently. Napa RCD offers a free service to evaluate irrigation systems to ensure even water distribution. These evaluations focus on measuring uniformity of irrigation water applied throughout the vineyard. Results from the irrigation evaluation help growers easily identify opportunities to improve water use efficiency and performance of their irrigation systems and vines. ​ Learn more.

​Water Conservation & Management in the Vineyard

Watch the video in Spanish here

​Here are some things to keep in mind:

1. ​Maintenance and Flushing: Regular maintenance of irrigation systems, including flushing at the beginning and throughout the season, is crucial for preventing clogged emitters.
2. Emitter Lifespan: Netafim emitters typically last about 15 years, but many vineyards use them for longer, leading to potential issues with water distribution.
3. Consistency in Emitters: Combining different brands or ratings of emitters can lead to uneven water distribution and should be avoided.
4. Tools for Water Monitoring: Techniques such as visual inspections, pressure bomb measurements, and NDVI imaging can help determine plant water stress and guide irrigation decisions.

Top 10 Vineyard Recommendations for Saving Water and Energy

1. Use irrigation scheduling
Three main tools are at your disposal: weather based ET estimates (these will change year to year, you need at least one full station and additional precipitation and temperature stations), plant observations (leaf bomb), and soil measurements.
2. Assess soil types/depths and variations
The irrigation systems must be blocked out by soil types and depths, as well as by variety and plant spacing.
3. Measure/improve distribution uniformity (DU)
The DU for your irrigation system should be measured often, and be better than 0.85 on existing systems, and better than 0.92 on new systems. 

​​4. Keep good records – flowrates/volumes/timing
“If you don’t measure you can’t manage,” by keeping good records you can determine exactly where your attention should be directed.
5. Standardize sampling location
Sampling locations for soil moisture and for plant water status must be near “average” emitters to give an “average” result. There are multiple types of flow meters available, the most popular is a saddle-type propeller meter. However, megameters have some advantages: no moving parts, good for highly erosive and corrosive fluids, not impacted by sand, sediment, or algae.
6. Maintain regulated deficit irrigation (RDI)
Maintain a “consistent desired” stress for RDI.
7. Start the plant growth period (prior to bud break) with a full soil profile of water
8. Do not stress the vines until canopy achieved
Once the desired canopy size is achieved (or just before then), and after fruit set, reduce irrigation to stop tendril and shoot growth.
9. Moderate stress (or somewhat higher) should be maintained until veraison
This may equate to irrigating at “50% of full ETC
10. After veraison, increase the irrigation frequency to maintain turgid berries and maintain the canopy
Do not allow vegetative growth the restart. This means it is good to have some RDI. Protect the fruit (do not lose leaves). This means that excessive RDI is harmful. 

Recycled Water

Recycled water is wastewater effluent that has been further treated and disinfected to provide a non-potable (non-drinking water) water supply. Recycled water is safe and suitable for uses such as vineyard irrigation and is an environmentally responsible way to conserve scarce and expensive water supplies. Learn more at Napa Sanitation District.

Additional Resources

2024 Sustainable Vineyard Practices: Irrigation 
Dr. Gregory Gambetta, ​Professor of Viticulture, Institut des Sciences de la Vigne et du Vin / Bordeaux Sciences Agro

2023 Sustainable Vineyard Practices: Advancing Irrigation Technology in the Vineyard
Dr. Stuart Styles, Cal Poly San Luis Obispo

2022 Sustainable Vineyard Practices: Drought & Irrigation
Dr. Andrew McElrone, Associate Adjunct Professor, USDA-ARS; UC Davis
Dr. Elisabeth Forrestel, Assistant Professor, UC Davis
 Dr. William Kustas, USDA-ARS Hydrology & Remote Sensing Lab

2023 Water Conservation Seminar: ​Drought Farming Strategies 
Randy Heinzen, Vineyard Professional Services
Will Thomas, Foley Family Farms​

2022 Rootstock: All Things Water – The Key to Resilient Farming
Garrett Buckland, Premiere Viticultural Services
Sarah Ferguson, Silverado Farming Company
Justin Leigon, Pina Vineyard Management

NVG Best Practices Paper: Irrigation*

* Requires NVG Member login to access