Water Worries Mendocino Grapegrowers

Anderson Valley vintner expects driest season since 1977

by Jane Firstenfeld
Alternative text
Fog blankets Husch Vineyards in Mendocino County's Anderson Valley, which this year may face severe water restrictions.
Boonville, Calif. -- An owner of Anderson Valley's Husch Vineyards ran the numbers and says his statistical model suggests that this year, grapegrowers in his corner of Mendocino County will face the most dire water shortage since the severe drought of 1977. Looking back even further, Zac Robinson's regression model indicates the Navarro River that drains Anderson Valley could have its second lowest summer flow since 1952.


View Navarro River in a larger map
Robinson shared his findings during the Anderson Valley Pinot Noir Festival Technical Conference at the Mendocino County Fairgrounds May 15. A panel on Water Use and Current Situations for Vineyards and Wineries also included Glenn McGourty, University of California viticulture and plant science advisor for Mendocino and Lake counties, and Laurel Marcus of Fish Friendly Farming, a certification and education program of the California Land Stewardship Institute. Husch Vineyards is certified Fish Friendly, and Zac Robinson suggested that the current arid conditions threaten both the fish and the farmers.

According to Robinson's figures, the Navarro watershed averages 48 inches of rainfall per year; so far this year's precipitation is less than 60% of that, and the shortage is compounded by groundwater levels diminished by the two previous years, when rainfall also was below average. If the valley has average summer weather, the river could flow at its lowest level in 32 years.

Alternative text
Robinson also charted a shift in the pattern of rainfall, and reported that autumn rains now start about two weeks later than they did a few decades ago. The good news is that spring rains tend now to linger about 10 days longer than in the past, helping maintain river flow longer. He also noted a "mystery factor"--river flow diminished by about 1-cubic-foot per second per eight years. He and other observers in the audience speculated this diminution could be caused by household use, wells, illicit pumping from the river, undocumented vineyard usage, or even illegal crops, not unheard of in Mendocino County.

Whatever the culprit(s), environmentalists are concerned on behalf of salmon, which use rivers such as the Navarro to spawn and replenish their dwindling population. And, McGourty told Wines & Vines, vineyards in particular are obvious targets, especially when water is sprayed for frost protection. "It's pretty visible." That high profile tends to spawn public outcry, even though the winegrape industry is Mendocino County's biggest agricultural producer (see "Wine Water Issues Simmer," May 6).

According to McGourty, Mendocino vineyards require an average of 3 inches per acre of water for growing season irrigation; frost protection may double that figure. Fortunately, as spring turns to summer, the possibility for potentially damaging frost this year decreases daily.

Alternative text
Zac Robinson, who owns Husch Vineyards with his family, studied historical patterns of precipitation, and learned that this could well be the driest year since the drought of 1977.
McGourty confirmed, however, that should river levels fall to a point that officials deem dangerous to the salmon, farmers who have legally used their traditional riparian rights to tap directly into rivers, tributaries and ponds fed by them can be forbidden to use that source of water. In that case, the alternatives to dry farming include sources such as well water (ground water is not regulated in California) and trucking in tanks of purchased water.

The University of California, McGourty said, is currently doing a water study, evaluating agricultural use of the ever-more-precious commodity. In the meantime, he advised, "Everybody has an impact. We're all in this together."

View more details of Robinson's work at http://avwines.com/river.pdf.
Currently no comments posted for this article.