The plant is called water hyacinth. It's a weed that grows on top of the water blocking sunlight from reaching native aquatic plants and starving the water of oxygen, and that can kill fish.
Gloria Sandoval with the state Department of Boating and Waterways says the weed - with its green, glossy leaves and lavender flowers - also clogs marinas.
"It's actually a very beautiful plant. But the effects that the presence of this plant could have on the delta's ecosystem and we also are looking at it from a public safety issue - navigation."