
Current lab members

Nerissa Barling
PhD Student
Growing up in Hawai'i, Nerissa's curiosity about ahupua'a, local watersheds, propelled her interest in stakeholder and enquiry-driven science. She graduated from Colorado College with a Bachelor's degree in Geology and joined the Zimmer Watershed Hydrology lab in the summer of 2021. Passionate about research that informs policy, Nerissa is building her scientific toolkit to investigate how the physical structure of the subsurface controls water storage, plant-water supply, and streamflow generation. She hopes to apply her scientific knowledge of hydrologic systems toward meaningful actions that benefit local community members and ecosystem management.
PhD Student
Growing up in Hawai'i, Nerissa's curiosity about ahupua'a, local watersheds, propelled her interest in stakeholder and enquiry-driven science. She graduated from Colorado College with a Bachelor's degree in Geology and joined the Zimmer Watershed Hydrology lab in the summer of 2021. Passionate about research that informs policy, Nerissa is building her scientific toolkit to investigate how the physical structure of the subsurface controls water storage, plant-water supply, and streamflow generation. She hopes to apply her scientific knowledge of hydrologic systems toward meaningful actions that benefit local community members and ecosystem management.

Russell Callahan
Postdoctoral Scholar
Russell received his B.S. in Environmental Science from Montana State University in 2015 and his Ph.D. in Geology from University of Wyoming in 2021. He joined the Zimmer lab as a Postdoctoral Researcher in the summer of 2022. Russell is excited to use his knowledge of weathering, near-surface geophysics, and geomorphology to understand deep weathering processes at Blue Oak Ranch Reserve.
Postdoctoral Scholar
Russell received his B.S. in Environmental Science from Montana State University in 2015 and his Ph.D. in Geology from University of Wyoming in 2021. He joined the Zimmer lab as a Postdoctoral Researcher in the summer of 2022. Russell is excited to use his knowledge of weathering, near-surface geophysics, and geomorphology to understand deep weathering processes at Blue Oak Ranch Reserve.

Amanda Donaldson
PhD Student
Amanda joined the Zimmer lab in Summer 2018. She received a Bachelor’s degree from Humboldt State University in Forestry with an emphasis in hydrology. Her current research investigates how critical zone form influences water flow and storage, and conversely, how water dynamics affect critical zone functions. Her ultimate goals are to improve our understanding of water partitioning throughout the landscape and reveal patterns or processes that aid in more efficient water resource management.
PhD Student
Amanda joined the Zimmer lab in Summer 2018. She received a Bachelor’s degree from Humboldt State University in Forestry with an emphasis in hydrology. Her current research investigates how critical zone form influences water flow and storage, and conversely, how water dynamics affect critical zone functions. Her ultimate goals are to improve our understanding of water partitioning throughout the landscape and reveal patterns or processes that aid in more efficient water resource management.

Lauren Giggy
PhD student
A central coast of California native, Lauren received her B.S. in Geology and GIS Certificate from Fort Lewis College in Durango, Colorado. Her research interests include surface-groundwater interactions, biogeochemistry, geomorphology, and watershed hydrology. She is eager to apply her geologic perspective to the interdisciplinary nature of water resource studies with the Zimmer Lab beginning in Fall 2019.
PhD student
A central coast of California native, Lauren received her B.S. in Geology and GIS Certificate from Fort Lewis College in Durango, Colorado. Her research interests include surface-groundwater interactions, biogeochemistry, geomorphology, and watershed hydrology. She is eager to apply her geologic perspective to the interdisciplinary nature of water resource studies with the Zimmer Lab beginning in Fall 2019.

Emilio Grande
PhD Student
Emilio Grande graduated in 2017 with a BS in Geology and in 2019 with a MS from Cal State East Bay. Emilio’s main research interest is isotopes hydrology to understand groundwater-surface water exchanges, transit time distribution and effects of land use on water quality. His past research was focused on the use of geochemical tracers and stable isotopes of water to characterize water sources and nutrient transport in a small catchment in Berkeley, California. He is applying this toolkit to understanding similar questions at the Blue Oak Ranch Reserve. In his free time, he enjoys backpacking, reading, bicycling, running, sailing and hiking.
PhD Student
Emilio Grande graduated in 2017 with a BS in Geology and in 2019 with a MS from Cal State East Bay. Emilio’s main research interest is isotopes hydrology to understand groundwater-surface water exchanges, transit time distribution and effects of land use on water quality. His past research was focused on the use of geochemical tracers and stable isotopes of water to characterize water sources and nutrient transport in a small catchment in Berkeley, California. He is applying this toolkit to understanding similar questions at the Blue Oak Ranch Reserve. In his free time, he enjoys backpacking, reading, bicycling, running, sailing and hiking.

Adam Haynes
PhD student
Adam Haynes graduated in 2017 with a B.S. from Michigan State University and received his M.S. from the University of Connecticut in 2021. Adam joined the Zimmer lab in the Fall of 2021 and will be assisting in the creation of a Reactive Transport Model for the Elkhorn Slough Watershed. His interests include human impacts on aquatic ecosystems and hydro-biogeochemistry; surface water/groundwater exchange processes and modeling; the transport/fate of toxins and other pollutants between terrestrial and aquatic ecosystems; watershed and stream restoration.
PhD student
Adam Haynes graduated in 2017 with a B.S. from Michigan State University and received his M.S. from the University of Connecticut in 2021. Adam joined the Zimmer lab in the Fall of 2021 and will be assisting in the creation of a Reactive Transport Model for the Elkhorn Slough Watershed. His interests include human impacts on aquatic ecosystems and hydro-biogeochemistry; surface water/groundwater exchange processes and modeling; the transport/fate of toxins and other pollutants between terrestrial and aquatic ecosystems; watershed and stream restoration.

Maya Montalvo
MS student
Maya joined the Zimmer Lab as an undergraduate in the spring of 2019 assisting in research of hydrologic and biogeochemical processes at the Elkhorn Slough. She graduated with a B.S. in Earth Science and Environmental Geology in June of 2020 and continued on as an M.S. student at UC Santa Cruz in the Zimmer Lab. Maya is using geochemical tracers and stable isotopes to study groundwater-surface water interactions and nutrient transport for her research at the Elkhorn Slough. Maya enjoys the outdoors and goes rock climbing, backpacking, hiking, and biking when possible.
MS student
Maya joined the Zimmer Lab as an undergraduate in the spring of 2019 assisting in research of hydrologic and biogeochemical processes at the Elkhorn Slough. She graduated with a B.S. in Earth Science and Environmental Geology in June of 2020 and continued on as an M.S. student at UC Santa Cruz in the Zimmer Lab. Maya is using geochemical tracers and stable isotopes to study groundwater-surface water interactions and nutrient transport for her research at the Elkhorn Slough. Maya enjoys the outdoors and goes rock climbing, backpacking, hiking, and biking when possible.

Michael Wilshire
Lab Tech
Michael joined the Zimmer lab in September 2020 after graduating from UCSC with a B.S. in the Environmental Sciences. His current role ranges from Lab Manager to Research Technician. Outside of work, Michael enjoys cycling through the Santa Cruz mountains, surfing, and playing piano.
Lab Tech
Michael joined the Zimmer lab in September 2020 after graduating from UCSC with a B.S. in the Environmental Sciences. His current role ranges from Lab Manager to Research Technician. Outside of work, Michael enjoys cycling through the Santa Cruz mountains, surfing, and playing piano.
Distinguished Alumni
Jonathan Swanson (MS student, graduated 2020)
Andi Greene (MS student, graduated 2020) - now Restoration Ecologist at HT Harvey and Associates
Loren Tolley-Mann (undergraduate senior thesis student, graduated 2020) - now Staff Geologist at Trinity Source Group
Chris Causbrook (undergraduate researcher, graduated 2020) - now Staff Geologist at Trinity Source Group
Zev Fellenbaum (undergraduate senior thesis student, graduated 2019) - now Staff Geologist at Trinity Source Group
Noah Lyman (undergraduate senior thesis student, graduated 2019) - now MS student at Cal Poly
Maia Hoffman (Lab Manager 2018-2019) - now Water Quality Technician at Denver Water
Peter Willits (Lab Manager 2020-2021) - now Geologic Technician at Environmental Investigation Services
Andi Greene (MS student, graduated 2020) - now Restoration Ecologist at HT Harvey and Associates
Loren Tolley-Mann (undergraduate senior thesis student, graduated 2020) - now Staff Geologist at Trinity Source Group
Chris Causbrook (undergraduate researcher, graduated 2020) - now Staff Geologist at Trinity Source Group
Zev Fellenbaum (undergraduate senior thesis student, graduated 2019) - now Staff Geologist at Trinity Source Group
Noah Lyman (undergraduate senior thesis student, graduated 2019) - now MS student at Cal Poly
Maia Hoffman (Lab Manager 2018-2019) - now Water Quality Technician at Denver Water
Peter Willits (Lab Manager 2020-2021) - now Geologic Technician at Environmental Investigation Services