Meteor Vineyard
Lauren Betts
March 12, 2014 | Lauren Betts

Groundwater & Irrigation in the Napa Valley

Groundwater conditions in Napa Valley were broadly stable throughout 2013 however, we still need to continue the practice of conservation in our vineyards.

The groundwater levels on the Napa Valley floor show stable long-term trends with generally good quality water. As of March 10, 2014 we have received 40-50% of total rainfall for our year and those numbers could still grow in the remaining weeks.  This is less rainfall than the average year, however, most of Napa County received much-needed, ground-soaking rain in February and March.  Most vineyard ponds and reservoirs are now full or nearly full in time to meet irrigation needs for the 2014 growing season. 

Residents, businesses and agriculture rely upon groundwater for drinking water, irrigation and the environment.  These demands make it essential for us to preserve groundwater quality and availability long-term in order to meet water needs during drought and to prevent any potential negative environmental effects in the future.

We as a vineyard need to continuously monitor groundwater conditions while taking measures to utilize less water to ensure we have a stable long-term supply. 

Here are 5 conservation tips from Meteor Vineyard Manager, Mike Wolf:

1.  Examine your irrigation systems and make adjustments as necessary.  If something’s not working, fix it!  Systems older than 5 years should be tested to ensure efficiency.

2.  The most efficient time to irrigate a vineyard is at night.  Watering during the day is a waste!

3.  Know your dew points; this tool can help you effectively determine when it’s necessary to irrigate.

4.  Keep your cover crops in check!  During a drought year, vigorous cover crops could be taking away water available for the vine.  Mow then short.

5.  Determine what size canopy can effectively manage with less water available.  This may result in smaller, but better-balanced vines.

Data from a new study by the Napa County Groundwater Advisory Committee indicates our groundwater and aquifer resources are very healthy despite the lack of rain.  This makes Napa County unique compared to other farming communities in California that face zero to small water allocations this year. 

Napa’s vintners and growers continue to employ the most up-to-date technology to monitor water resources; these can determine at the vineyard block and sometimes at the vine level where water is needed to help source the water we have in to the correct places. 

University of California’s Agriculture & Natural Resources department provides a strategy to follow for irrigation methods to minimize loss in yield during a season:

Bud break to flowering:  Avoid water stress.  This is critical for root growth, canopy establishment and yield for current season.

Flowering to fruit set:  Avoid high water stress at flowering: poor fruit set, aborted fruit shoots still growing rapidly; maintain good soil moisture when water limiting, do not promote large canopy with early water & avoid sunburn by limiting excessive leaf removal in fruit zone. 

Fruit set to veraison:  Vine less susceptible to moderate water deficits, control shoot growth, reduce berry size and reduce water use without impacting fruit quality.

Veraison to harvest:  Avoid severe water deficits to maintain healthy leaf function to promote barry maturation. 

Harvest to leaf fall (and over winter):  Some soil moisture needed to maintain leaf function to build reserves.  Reserves impact cold hardiness (especially in young vines).

Grapevines can not only survive but also sometimes even thrive with limited water.  While growers might face more challenges with a smaller water supply, they will use management techniques for their crop and canopies to counteract the effects of low water levels.  With the correct management of the crops, the yield might be lower but the crop quality can still be high. 

The 2014 Napa Valley Vintners Community and Industry Issues Committee (CIIC) will focus on local issues that directly affect the wine industry and is a great resource for questions regarding Napa Valley groundwater and irrigation.    

Spokesperson from NVV said, “At the end of the day, vintners and grape growers are farmers.  As no two growing years are the same, farmers must successfully adapt, harvest to harvest, season to season, year to year and have done so for nearly two centuries in Napa Valley, and for thousands of years worldwide.  No matter what 2014 brings Napa Valley’s vintners and growers, they will continue to adapt and change their practices to make the best quality wines under any circumstance.”


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