Sienna White

The Sacramento-San Joaquin Delta is a place of extraordinary cultural, historical, and ecological significance. Formed by the convergence of the Sacramento and San Joaquin River, the Delta drains approximately 40% of California’s land. Its headwaters have and continue to be central to subsistence practices by Indigenous peoples; recreation in the Delta includes world-class fishing and duck hunting; and the Delta’s few remaining tidal marshlands serve as critical habitat to millions of migrating birds each year.

The Delta receives large inputs of anthropogenic nutrients from wastewater treatment plants which result in elevated dissolved inorganic nitrogen levels. This nutrient-enriched status places the Delta at high risk for algal blooms, including risk for bloom events with toxic, or harmful algal species (commonly referred to as harmful algal blooms, or HAB events). These harmful algal blooms threaten public health and endanger the potability of the water supply. Furthermore, climate change, reduced sediment load, and increased nutrient delivery have accelerated algal bloom activity, resulting in increased harmful algal bloom events.

My PhD research focuses on using numerical models to investigate the specific mechanisms that precipitate harmful algal blooms, which likely involves a "goldilocks zone" of wind-driven mixing, tidal forcing, river outflow, nutrient supply, and temperature. Better understanding what conditions allow Microcystis (a harmful algal species) to dominate over beneficial algal species will inform a predictive framework, providing water managers with much-needed visibility of where (and when) harmful algal blooms are likely to occur.