May 8: Science Speaker Series presents Dr. Carrie Monohan

As part of the Sierra Science Series, Dr. Carrie Monohan will be giving a free lecture titled: “Sediment and Mercury Loads from Creeks to Reservoirs Represent a Golden Opportunity” at the Sierra College in Grass Valley.

More than 10 million pounds of mercury were used during hydraulic and hard rock mining during the California Gold Rush, and it is estimated that up to 30% of liquid mercury was lost to the environment. Mercury from mining debris is entrained in river gravel and incorporated into the aquatic food web, causing numerous environmental and public health problems for California communities today. Mercury-contaminated sediment is still being discharged from legacy mine sites, this material accumulates in reservoirs, including the Combie Reservoir. The Nevada Irrigation District has developed a 3 to 5 year project to dredge contaminated sediment from Combie Reservoir while implementing an innovative recovery process to remove the free elemental mercury from the dredged material. The project would remove and treat an estimated 100,000 cubic meters of sediment from the upstream reach of the reservoir. The dredged material will be passed through a specialized centrifuge, thereby removing mercury as well as other heavy minerals, including gold.

Tuesday, May 8th, 2018
6:00–6:30 pm Refreshments
6:30-7:30 pm Presentation
Sierra College Multipurpose Center N12
250 Sierra College Dr., Grass Valley

Carrie Monohan, Ph.D., is the science director at The Sierra Fund (TSF). She executes TSF’s Ecosystem Resiliency Program, which addresses ongoing mining impacts on water quality, forest health, meadows and fish passage. For over 10 years, Dr. Monohan has researched the effects of the Gold Rush in the Sierra Nevada. Her assessment techniques and efforts to prioritize mine-scarred lands have helped shape statewide efforts to reduce mercury discharge from California’s headwaters.

Dr. Monohan is an Adjunct Professor in the Geological and Environmental Sciences Department at CSU Chico, where she builds the capacity of early career scientists by integrating graduate student research into the projects that she directs at TSF. Her projects include work at Malakoff Diggins and management of sediment and mercury from Combie Reservoir.