Dr. Gus Tolley’s presentation “From Mountains to Valleys: The Connection Between Groundwater and Surface-Water” as part of the Sierra Streams Institute Science Speaker Series has been postponed due to campus closure.

About the topic: Although surface-water flow is relatively easy to understand since it can be physically observed, groundwater flow is much more obscure since it is practically invisible. Despite its mysterious nature, groundwater accounts for about 40 to 60% of our water supply. In California, groundwater aquifers can store more than 15 times the volume of all surface-water reservoirs in the state combined, making them a valuable asset during prolonged droughts. This presentation will demystify groundwater and explain how it is intimately connected to surface-water. Results from research conducted in mountainous watersheds in New Mexico and Colorado, and an alluvial groundwater basin in Northern California, are used to illustrate processes such as recharge, flow, discharge, and streamflow depletion.

Dr. Tolley recently rejoined our team in northern California—he worked with DBS&A in California and New Mexico prior to earning his PhD in Hydrology from University of California-Davis.

Dr. Tolley specializes in:

  • Groundwater hydrology
  • Groundwater resources
  • Engineering hydrology
  • Contaminant transport in groundwater
  • GIS mapping

His background with numerical modeling and surface water-groundwater interactions is beneficial to many of the GLA companies’ water planning and development, mining, solid waste, and litigation clients throughout the West, including Groundwater Sustainability Agencies (GSAs).