Pacific Swell | Southern California environment news and trends

Trout, salmon threatened by water shortages in California wine country

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Generally, wine and fish can be paired quite nicely. In California wine country, however, the relationship between the two has not been so harmonious. New research has found a correlation between markedly higher death rates in steelhead trout with lowered summer water levels and the amount of vineyard acreage upstream.

The study, conducted by biologists at UC Berkeley, discovered that the fish are especially vulnerable during the drier months of summer. They found only 30 percent of the juvenile trout present in June survived to see the end of the season. The number of surviving fish increases in years with more rainfall and in watersheds with less vineyard activity.

"Nearly all of California's salmon and trout populations are on the path to extinction and if we're going to bring these fish back to healthy levels, we have to change the way we manage our water," said Theodore Grantham, lead author of the study in Science Daily. "Water withdrawals for agricultural uses can reduce or eliminate the limited amount of habitat available to sustain these cold-water fish through the summer. I don't suggest we get rid of vineyards, but we do need to focus our attention on water management strategies that reduce summer water use. I believe we can protect flows for fish and still have our glass of wine."

The myriad uses vineyards have for water (ranging from irrigation to overhead sprinkler systems) are the root of the problem, with Grantham suggesting offstream reservoirs to store water during heavy rainfalls. That way, vineyards wouldn’t have to drain area streams during periods of low flow.

The study was based on nine years of fish count information across nine streams in Sonoma County. 

"This is the first scientific publication on how vineyards and summer stream flows relate to fish survivorship in California's tributary streams," added study principal investigator Adina Merenlender. "These findings will help inform an important environmental issue in California that is disturbing to conservationists and grape growers alike."