Water Hyacinth

  • About Facts Report a Sighting Updates
    • Water Hyacinth is an attractive floating aquatic plant with shiny green leaves and delicate lavender flowers.
    • It was introduced into the Delta from South America more than 100 years ago.
    • This extremely prolific aquatic invasive plant can double in size every ten days in hot weather and can quickly become a dense floating mat of vegetation up to six feet thick.
    • The mats can travel with river currents and with tidal movement.
    • Mats can also attach to structures in the water, limiting access to boats and reducing swimming areas.

    • The species is too well established in the Delta region, eradication is impossible.
    • There is no known eradication method in the world for water hyacinth. Therefore, DBW operates a control program as opposed to an eradication program.
    • DBW has the authority to cooperate with other state, local and federal agencies in controlling water hyacinth in the Delta region, its tributaries and the Suisun Marsh.
    • Surveys are conducted in the Delta to determine where water hyacinth is located and which areas are in most need of treatment. Surveys are also conducted to determine what agricultural crops are growing near treatment sites.
    • DBW works with the US Department of Agriculture to obtain the required approvals for conducting the Water Hyacinth Control Program from the United States Fish and Wildlife Service and the National Marine Fisheries Service (part of National Oceanic and Atmospheric Administration). These two approvals are required by the Endangered Species Act.
    • A third approval, a National Pollutant Discharge Elimination System permit is required by the Central Valley Regional Water Quality Control Board.
    • The approval process determines if herbicide usage may affect any of the threatened, endangered or sensitive species, and critical habitats. Effects to humans, agricultural areas or potable water intakes are also reviewed.
    • Approvals place restrictions on where DBW can treat the plants, when and where the program can start herbicide treatments (this varies throughout the Delta region), and an extensive water monitoring program. Extensive water quality sampling is conducted at treatments sites throughout the season to ensure herbicide levels stay within the required limits.
    • Water hyacinth is chemically treated with glyphosate or 2,4-D. Herbicides are registered for aquatic use with California Environmental Protection Agency and the California Department of Pesticide Regulation. The herbicides are contact herbicides in liquid form, sprayed directly onto the water hyacinth.
    • Initial symptoms of glyphosate treatment on water hyacinth do not appear for two weeks or more. Visible treatment symptoms are gradual wilting and yellowing of the plant, advancing to browning of vegetation and eventual decay. It may take two months for herbicide effectiveness to be clearly visible.
    • Funding for water hyacinth treatment comes from the Harbors and Watercraft Revolving Fund, which receives revenues from boaters’ registration fees and gas taxes.
    • If you sight water hyacinth, please call the Division of Boating and Waterways (DBW) at (888) 326-2822 or send an e-mail to pubinfo@parks.ca.gov.  Include in your message the address or nearest landmark of the sighting.  If possible, take photographs of the plant.

    California Division of Boating and Waterways will begin its 2013 Water Hyacinth Control Program in selected areas of the Delta starting Mar. 18, 2013 through Nov. 30, 2013.

    There are some Delta sites that DBW will not currently treat at this time in order to protect listed salmon species and delta smelt. Treatment in these areas will begin later in the year after peak spawning and migration times when listed fish are less likely to be present.

    Treatment areas 2 - 4: Mar. 18 - Nov. 30, 2013

    Treatment area 1: June 1 - Nov. 30, 2013

    Treatment sites are subject to revision based on governmental requirements, weather conditions, plant growth, waterway traffic and fish presence surveys.

    Public Notice