By Fred Allebach
The Arroyo Seco watershed takes up approximately the eastern third of the lower Sonoma Valley. The Arroyo Seco channel was the original eastern boundary of the town of Sonoma. The whole of Eighth Street East, and up Castle Road, is the western boundary of this watershed. Agriculture easily takes up 60 percent of the land and water use. Buena Vista and Burndale are the two major unincorporated population centers.
Groundwater and seasonal surface flow are the only sources of water in the Arroyo Seco watershed. The watershed has potentially serious supply issues, including groundwater depletion (overdraft), dry wells, arsenic and saltwater intrusion. These issues are made worse by drought and increasing demand.
The Arroyo Seco area has no water agency or collective controls. Residential, agricultural and light industry users can pump as much groundwater as they want. In some areas, supply is not matching demand and groundwater is receding. The water table is 80 feet below sea level at Denmark and Burndale Road. The Eighth Street East and Napa Street intersection area is one of the highest deep-well depletion areas in the valley.
What can concerned landowners and citizens do? A forum to address Arroyo Seco water issues already exists in the Sonoma Valley Groundwater Management Program (SVGMP). This group has regular meetings and welcomes citizen input; see schedules and agendas online at scwa.ca.gov/svgroundwater/.