From the Department of Water Resources:
To help Groundwater Sustainability Agencies (GSAs) appropriately address depletions of interconnected surface water (ISW) in their Groundwater Sustainability Plans, the Department of Water Resources (DWR) today released the first in a series of three papers that will discuss the technical aspects of ISW and quantification of depletions of ISW due to pumping. These three papers will form the basis for a guidance document that DWR will publish for GSAs to consider when establishing ISW sustainable management criteria to manage depletions in their groundwater basins.
Under the Sustainable Groundwater Management Act, GSAs must provide their best estimate of the location, quantity, and timing of depletions of ISW and decide the conditions where depletions of ISW, due to groundwater pumping, become significant and unreasonable (i.e. an undesirable result). Further, the GSA must set minimum threshold(s), which are quantitative value(s) that indicate an undesirable result may be occurring.
The first paper, Depletions of Interconnected Surface Water: An Introduction, defines what ISW is and how it is identified. It also discusses basic concepts of depletions of ISW and important considerations when thinking about the management of depletions. The audience for Paper 1 is primarily GSAs and other interested parties, with both technical and non-technical audiences in mind.
Papers 2 and 3, anticipated to be released later this year, will go into more technical detail on approaches and examples for estimating depletions from groundwater pumping. These three papers will provide the foundation for DWR’s ISW guidance document on management of depletions of ISW, also anticipated for release later this year.
Paper 1 and all subsequent ISW documents will be posted on DWR’s Best Management Practices and Guidance Documents webpage under the heading of Guidance Documents. The webpage will continue to be updated with the latest information on DWR’s progress on ISW guidance. A direct link to download Paper 1 is here. Further information about the papers and guidance document can be found on DWR’s Best Management Practices and Guidance Documents webpage and in an ISW information sheet. For questions, please email sgmps@water.ca.gov.
