REGIONAL GROUNDWATER QUALITY MONITORING: COORDINATING SCIENCE WITH POLICY AND MANAGEMENT

On local to global scales, future water issues demonstrate the need for regional resources assessments, development of coordinated regional water resources monitoring programs, and effective use of hydrologic data to evaluate current groundwater conditions and long-term water quality and availability. In 2002, California passed legislation requiring local water agencies and other entities to prepare groundwater or integrated water resources management plans to be eligible for state funds to build water-related projects. The new requirements also require comprehensive groundwater, surface water, and subsidence monitoring programs to assess changes in basin conditions. The science community plays an important role by applying scientific principles and methods and thus more effectively using regional monitoring data to assess the management actions needed to address water resources quantity and quality issues.

A California grant program enabled implementation of a regional groundwater-monitoring project in Yolo County as an integral aspect of water resources management. This project led to a broader awareness of available water resources data and how those data can be better used to assess current groundwater conditions and trends indicating the vulnerability of the aquifer system to groundwater quality degradation. An earlier countywide study projected future increases in groundwater salinity; however, this study was not linked to an ongoing regional monitoring and management program. Recent project results highlighted continued salinity increases in the shallow and intermediate zones of the aquifer system especially in a subbasin with the most urban development. Correspondingly, municipal groundwater supplies are being explored and developed at greater depths to obtain improved water quality, while private domestic supplies typically draw from the shallower aquifers. Limited testing is required following construction of private wells; however, no subsequent local or state regulatory oversight occurs to ensure adequate quality. Consequently, impaired groundwater quality of shallow aquifers poses a significant water quality issue. Better coordination between policy makers and scientists needs to occur to improve information used to assess and manage water resources.