Led by the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) Areawide Pest Management Program, a collection of federal, state and local organizations and university researchers are successfully and safely managing the invasive aquatic weeds that have long plagued one of California’s key agricultural regions. 

The Sacramento-San Joaquin River Delta (known locally as “the Delta”) of northern California is the hub of the water distribution system for domestic water for 27 million people and provides irrigation water for $30 billion in crops annually in California’s Central Valley.  

However, the Delta is plagued by invasive aquatic weeds, and chronic drought exacerbates these problems. The most damaging invaders include floating aquatic vegetation (FAV) weeds such as water hyacinth, and submersed aquatic vegetation (SAV) weeds such as egeria or Brazilian waterweed. Riparian (shoreline) weeds like arundo invade levees and shorelines.  

Local, state and federal stakeholders and policymakers have called for action, but the complex interweaving of regulations imposed by federal, state, regional and county governments creates numerous issues that prevent a “business as usual” approach to managing invasive aquatic plants. 

The project also facilitated collaboration among federal, state, regional and local agencies with interests in managing invasive weeds in the Delta, starting with the state Division of Boating and Waterways (DBW).  

In response, the ARS, the National Aeronautics and Space Administration (NASA) Ames Research Center, California state agencies and university researchers formed the Delta Region Areawide Aquatic Weed Project (DRAAWP) in 2014. The project’s mission was to develop an adaptive management approach that would control invasive FAV and SAV while mitigating potential environmental impact. The project also facilitated collaboration among federal, state, regional and local agencies with interests in managing invasive weeds in the Delta, starting with the state Division of Boating and Waterways (DBW).  

The project’s successes to date include: 

• NASA’s satellite-based remote sensing technology was used to identify “nursery” areas where weeds persist year-round, targeting them for proactive management. Biological control was implemented by ARS and DBW across the Delta for waterhyacinth and arundo. Several new herbicides were cleared for use in the region, and mechanical removal was implemented strategically.  

• The integrated, adaptive management framework was implemented for control of four FAVs, five SAVs and arundo, far beyond the original focus of one FAV and one SAV. New control approaches were incorporated into major federal and numerous state regulatory permits and other documents covering the next five years of control operations through 2023, beyond the end of the DRAAWP.   

• The remote-sensing technology mentioned earlier was also used for monitoring and documentation, along with photo-monitoring, bioacoustics monitoring, and extensive sampling. DBW is now able to demonstrate to stakeholders how much control has been achieved for both floating and submersed species. In addition, ARS is able to document the efficacy of new chemical and biological control tools. 

• Aquatic weed control costs to stakeholders such as the U.S. Bureau of Reclamation, the Port of Stockton, and marina operators have been reduced by 33% to 100%. The project has generated more than $44 million in non-federal funding for state and local agencies; the ARS areawide investment in DRAAWP was $4.45 million. 

The project’s accomplishments were communicated to the public through stakeholder meetings, a website, research-focused symposia, journal articles, and presentations to policymakers. One of the ARS scientists has edited a 14-paper special issue of the Journal of Aquatic Plant Management focused entirely on the DRAAWP, which should be published this winter.