North Coast grape growers are look at water conservation options.“Water supplies for irrigating many vineyards are likely to be reduced in 2009 due to lower than average winter and spring rainfall the previous two years coupled with less than 1 inch of rainfall in January,” says Nick Frey, president, Sonoma County Winegrape Commission, Santa Rosa, Calif.
Sonoma County Water Agency (SCWA) projections for summer reservoir storage prompted a reduction to instream flow rates in the Russian River in early February to reserve sufficient water in Lake Mendocino. North Coast growers farming in the Russian River watershed or nearby will most likely be affected by water shortages.
The first step is to conserve soil moisture in the profile. That can mean early removal of cover crops (except near streams), disking, repeated mowing to limit cover crops, herbicide treatment or a combination of methods. Delayed initial irrigation is a second conservation measure.
Although frost protection is critical, growers are advised to watch dew point as well as air temperature. High dew points might warrant delaying the start of frost protection measures closer to temperatures approaching 32 degrees.
At the time when Lake Mendocino levels are projected to drop below 15,000 acre-feet, Chinook salmon will begin to migrate and spawn in the upper Russian River.
“Projections indicate that if water demand is not reduced and no more rain falls in our region, Lake Mendocino will run out of water and result in a lack of water in the upper Russian River by early fall,” says Dave Manning, SCWA principal environmental specialist. “We must have at least 15,000 acre-feet in Lake Mendocino by early fall for migrating and spawning Chinook salmon.”