Aquatic Weed Control Program

To contact us with questions or concerns regarding aquatic weeds in the Delta or this program, please call 1-888-326-2822 or email us at

Click Here To Join Our Weekly Treatment Notification

Program Description

In 1982, California state legislation designated the Division of Boating and Waterways (DBW) as the lead state agency to cooperate with other state, local and federal agencies in controlling Water Hyacinth in the Sacramento-San Joaquin Delta (Delta), its tributaries, and the Suisun Marsh.  The Egeria Densa control program was authorized by law in 1997 and treatment began in 2001.  The importance of both control programs is evident in that Water Hyacinth and Egeria Densa have a negative impact on the Delta’s ecosystem as they displace native plants, block light needed for photosynthesis, reduce the amount of dissolved oxygen in the water, and deposit silt and organic matter several times the normal rate.  Both aquatic invasive weeds are known to form dense mats of vegetation creating safety hazards for boaters, obstructing navigation channels, marinas and irrigation systems.

Additional Program Information:

  • Both plant species have no known natural controls in the Delta environment.
  • DBW’s Aquatic Weed Control Program obtains permits from the National Oceanic and Atmospheric Administration Fisheries, the U.S. Fish and Wildlife Service, and the Regional Water Resources Control Board.
  • DBW operates a “control” program as opposed to an “eradication” program. It is not likely that Water Hyacinth and Egeria Densa will ever be eradicated from Delta waterways.
  • DBW operates an extensive water quality monitoring program that shows that the control program meets water quality standards for herbicide use.
  • Permits restrict treatment in the Delta from March 1 through November 30th.
  • Annual hydro acoustic monitoring is done in the treatment regions to monitor changes in infestations over time.

For specific information, such as the treatment process, biological assessments and other reports, public notices and updates, please visit the division’s webpages for Egeria Densa and Water Hyacinth.