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.

External Resources

Napa County WICC
Napa County UCCE
​Napa RCD

​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.

Learn More

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.

More Resources

Additional content can be found on our Heat & Drought page.

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

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

2021 Sustainable Vineyard Practices: Vine Physiology & Irrigation 
Dr. Markus Keller, Washington State University