Date of Graduation
Master of Science in Environmental Management (MSEM)
College of Arts and Sciences
California uses more groundwater than any other state in the United States in order to meet agricultural demand during the growing season when water is naturally least available due to the state’s Mediterranean climate. The state also hosts populations of anadromous fish that are otherwise found exclusively in the wetter Pacific northwest. Groundwater has historically helped maintain baseflow in the summer and fall low-flow periods and acted as a natural buffer against the regular droughts that occur in California. Today, groundwater provides 30-40% of the state’s water supply, but the pumping in many cases has reduced groundwater discharge and baseflow, among other impacts, causing harm to anadromous fish populations. This paper explores the hydrogeologic conditions where groundwater extraction limits anadromous fish habitat. In the first section, a review of hydrogeology and well pumping explores the conceptual framework around the topic. In the second, third, and fourth sections, individual case studies are reviewed to explore the research question in specific contexts under a range of hydrogeologic conditions. Section two explores the Scott River aquifer in Northern California and impacts to coho salmon (Oncorhynchus kisutch) within a shallow, mostly unconfined alluvial aquifer. Section three studies the Cosumnes River aquifer in the Central Valley and impacts to fall-run Chinook salmon (Oncorhynchus tschawytscha) within a deep alluvial aquifer with heavily depleted groundwater supplies. Section four highlights the Pajaro Valley sub-basin where impacts to winter-run steelhead (Oncorhynchus mykiss) are limited by a confining layer in the upper portion of the alluvial aquifer. The conclusion provides an analytical framework for exploring this topic in other basins, considers the new Sustainable Groundwater Management Act of 2014, and the challenges of recovering groundwater in light of climate change.
Hebert, Aaron, "Impacts to Anadromous Fish through Groundwater Extraction" (2016). Master's Projects and Capstones. 366.