Napa Vineyards Hold Erosion at Bay

Protections in place following fall firestorm effective so far

by Kate Lavin
wine winery vineyard rain
Infrastructure should be examined for damage following a fire. Source: USDA Natural Resources Conservation Service

Napa, Calif.—The National Weather Service issued a flash-flood watch this afternoon in the San Francisco Bay Area, warning that “potential impacts from heavy rain include debris flows, mudslides, and flash flooding within the burn scars as well as locations downstream or downslope from the burn scars.”

Weather scientists said up to 4 inches of rain could fall in some parts of Northern California, but according to Philip Miller, deputy director of flood control and water resources for Napa County, flooding hadn’t been an issue as of Monday afternoon.

Miller and county staff distributed literature to property owners in the area, warning, “More than 70,000 acres within Napa County have burned. Vegetation that normally covers the hillsides is gone, creating the potential for higher levels of flooding, erosion and debris movement.”

Heidi Soldinger, marketing & communications manager for the Napa Valley Grapegrowers, spoke with several local vineyard managers today and learned the erosion-control measures put in place after harvest have been holding up.

“All of the main erosion-control practices took place in the winter, right against the end of harvest, such as making sure all irrigation and drainage areas are clear,” Soldinger said, adding that viticulturists were pleased the rain was enough to drench the soil, but not enough to cause mudslides and major damage. “They can now see how their best practices and all the erosion control that they put in place is faring. So they’re looking to see how drainage is doing right now and if there was any sort of waterways created for drainage.”

After the rain stops, Soldinger said growers will be going out into the vineyards to see how the water flowed during the storm and to use leaf blowers to make sure the waterways are clear of debris.

The Napa Valley Grapegrowers held a recovery session for vineyard managers in December, warning that growers should take care when removing downed trees and considering whether to cover hillsides with straw.

Santa Rosa, Calif-based The Wattle Guys donated wattles (rolls of straw to prevent erosion) for the event, and Soldinger said many growers had the rolls in place prior to the rains.

10 rules
The USDA outlined 10 rules for preparing vineyards (as well as orchards and rangelands) for the winter rainy season following a fire:
• Cover disturbed areas,
• Prevent soil disturbance,
• Evaluate roads and drainage facilities,
• Monitor and maintain existing measures,
• Use caution with emergency treatments,
• Treat high-hazard, fire-damaged trees,
• Consider debris barriers below rocky slopes,
• Seek professional assistance,
• Work with neighbors,
• Be prepared with evacuation plan.

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