Wednesday July 29, 2026
Maven’s Notebook —
Invasive aquatic vegetation has become one of the Sacramento-San Joaquin Delta’s most persistent challenges, affecting ecosystems, navigation, water operations, and public safety. The Delta’s mild climate, altered waterways, high nutrient levels, and complex network of sloughs and rivers create ideal conditions for non-native aquatic plants to spread rapidly and become difficult to control.
The extent of the problem varies widely from year to year, driven by seasonal temperatures, drought conditions, and river flows. Historical estimates for water hyacinth alone have ranged from fewer than 500 acres to more than 2,500 acres, while submerged weeds such as Brazilian waterweed can cover even larger areas. During recent drought periods, including 2013–2015 and 2021–2023, remote sensing data showed sharp increases in submerged aquatic vegetation as warm, slow-moving water created especially favorable growing conditions.
As these invasive plants expand, they can transform the Delta’s marsh habitats by slowing water velocities, increasing water clarity, providing cover for invasive fish, and reducing the open, turbid-water habitat needed by native pelagic species such as Delta smelt. Dense vegetation can also obstruct waterways, interfere with navigation, and clog agricultural and municipal water intakes. Left unchecked, invasive aquatic vegetation poses risks not only to native species and habitat, but also to boaters, agriculture, water supply operations, and public safety.