New monitoring wells needed after severe droughts, water losses

Pressure transducers, other devices pump data from groundwater wells

Three Sonoma Valley Groundwater Sustainability Agencies (GSA) have been monitoring groundwater through volunteered residential and commercial wells since 2017. However, four new monitoring wells designed to gather a broad range of data will soon provide more information to water supply and conservation as well as regulation.

California droughts from 2007 through 2009 and from 2012 through 2016 have resulted in severe groundwater losses. To better understand the link between groundwater and surface water and increase fresh water sustainability, the state Department of Water Resources (DWR) is providing technical coordination and underwriting construction costs to drill and implement data collection from the new wells.

Depending on agreements with property owners and environmental assessments, the drilling locations may change.

California DWR employee checks soil samples before monitoring well construction contractors dig. photo credit John Burgess, The Press Democrat, November 2019Sonoma Water project manager Mitchell Buttress (not pictured) explained, “The dedicated monitoring wells will be significantly more capable of producing good data relative to supply wells.

Sites have been strategically chosen to monitor discreet aquifer zones. In contrast, supply wells often span several aquifer zones.

The hydrogeologist added that without pumps and associated equipment typically found on supply wells, the new monitoring sites allow for the installation of pressure transducers or other monitoring devices. In addition to monitoring water level, the new sensing points can take water quality in account by measuring chlorides and other elements.

Telemetered devices were not included in design plans, but they can be installed later. Buttress clarified that “periodic manual water-level measurements” will be needed to calibrate transducer data, so Sonoma Water will still make quarterly field visits to the sites.

Sonoma Water spokesperson Ann Dubay added that data collected from these wells will be made available to the public via an online portal at Sonoma Water.

The grant from California DWR was made possible through the California Drought, Water, Parks, Climate, Coastal Protection, and Outdoor Access for All Act of 2018, which voters favorably supported as Proposition 68 that year.