Thomas Harter | Regulating Groundwater Pumping That Impacts Stream Ecosystems

Dr. Thomas Harter, professor at The University of California, Davis, gave a talk titled Regulating Groundwater Pumping That Impacts Stream Ecosystems: Integrated and Transdisciplinary Hydrologic Science at the Cutting Edge of California’s New Groundwater Law Abstract: The reduction and depletion of stream flow and lake levels due to groundwater pumping is an underappreciated impact of groundwater pumping with often devastating effects on ecosystems. California’s new groundwater law is one of few state and international water laws that explicitly attempt to protect “interconnected surface waters”. In this talk, I explore both, the scientific complexity of the groundwater-surface water-ecosystem connection and the complexity of the societal, legal, and administrative structures that have evolved around protecting groundwater-dependent ecosystems, using a case study from California. We have developed a novel integrated hydrologic modeling approach to provide decision-support to local, regional, and state regulatory agencies as they develop limits and management actions in negotiation with interested parties including environmental NGOs, tribal representatives, domestic well users, communities, and agricultural pumpers. Developing the decision-support tool has been a two-step process: development of a trusted baseline model capable of reproducing and explaining experienced hydrologic history, and development of future model scenarios to inform decision-making. I show how contributions of the community’s various actors, through their interactions with the model, affect the design of the model and how this community-engagement shapes planning and management design decisions. Clear, open, transparent, consistent, and educational communication with strong integrity is critically important to this process, between scientists and community/actors and between opposed factions of actors. A trusted hydrological model can disassemble some barriers to consensus building. But value-decisions remain as relevant to management design as scientifically based information.