Rapid, spatially explicit pesticides risk analyses in the Bay Delta Watershed and bridging the gap between risk assessment and management actions

Project Number
Project Date Range
Funding Agency
Delta Stewardship Council, Delta Science Program
Focus Area(s)
Education, Training and Public Information

The watershed of the San Francisco Bay and Delta (Bay-Delta) is home to a rich community of organisms that have suffered from chemical exposure, water withdrawal and habitat loss due to agricultural and urban development. A major contributor to chemical stress in the Bay-Delta watershed is pesticide use. Parker’s project modeled the spatiotemporal distribution of risk of all contemporary pesticides used in agricultural applications within 100 kilometers of the Bay-Delta. The model accounted for water management practices, diverse land characteristics, pesticide use rates and cumulative pesticide stress.


Research Conclusions 

​​The Pesticide Management Prioritization Model (PMPM) was developed to enable rapid assessment of pesticide toxic loads in the Bay-Delta watershed. Hundreds of different types of pesticides are applied each year at hundreds of sites across the watershed; the cumulative total volume of pesticides reaches into the tens of thousands of kilograms annually. 

An important contribution of the PMPM is the ability to consider individual and cumulative pesticide toxicity on specific species, allowing managers to better understand impacts to the diverse taxa of the watershed. The tool also quantifies the sources of pesticides and timing of toxic burdens to the waterbodies of the Bay-Delta. The PMPM achieves these aims with a user-friendly framework, designed to be accessible to diverse audiences, including local residents as well as experts.





Principal Investigators
profile photo of Nicol Parker Nicol Parker
University of California, Santa Barbara (UCSB)

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