Science activity

Invasive aquatic macrophytes (aquatic weeds) cover increased dramatically in the Sacramento-San Joaquin Delta during the 2013-2015 drought and the 2021-2023 drought. This trend toward increasing dominance of these invasive aquatic weeds has profound implications for delta/marsh habitat, as aquatic weeds are known to significantly alter the physical environment by slowing water velocities, increasing water clarity, providing habitat for invasive fishes, and reducing open water habitat. These habitat effects are thought to negatively impact the endangered Delta Smelt and other pelagic species that rely on turbid, open water habitat.

Different state and federal agencies have funded the acquisition of airborne spectroscopy data over the legal Delta since 2004. However, this long dataset has a critical 5-year gap in data acquisition during one of the most severe droughts that California has seen. This project is focused on inventorying any high spatial resolution satellite imagery that may have been taken over the legal delta, processing and analyzing it and mapping it to fill this 5-year gap in the only existing large-scale monitoring and mapping effort focused on aquatic macrophytes in the Delta. 

The main objective of the study is map the satellite "gap-fill" imagery using the same methods used for the spectroscopy airborne data and creating and publishing a time series of those maps that could then potentially be used as a 21-year continuous dataset of floating and submerged aquatic macrophytes distribution in the Delta. Further, these maps will be used to study the effect of nutrients and management activities on the distribution of these invasive species.