Egeria densa

  • About Facts Authority & Funding Program Restrictions Updates

    Egeria densa (Brazilian Elodea) is a shallow-water submerged aquatic plant from Brazil, popularly used as an aquarium accessory that was introduced into the Sacramento-San Joaquin Delta about 40 years ago (possibly from use in home aquariums). Egeria densa and other submerged vegetation now infest many thousands of surface acres of the Sacramento-San Joaquin Delta. The plant can spread very quickly depending on environmental conditions, often by fragmentation. The Division of Boating and Waterways (DBW) is the only entity authorized to treat Egeria densa in California with herbicides.


    Members of the public may contact DBW with questions or concerns relating to Egeria densa and treatment of this aquatic invasive species at (888) 326-2822 or e-mail the division at

    Include in your message the address or nearest landmark of the sighting. If possible, take photographs of the plant.


    Aquatic weeds currently treated by DBW in the Delta
    Aquatic weeds identified as potential problems by DBW in the Delta


    What is Egeria densa (Brazilian Elodea)?

    Can Egeria densa be eradicated?

    What effects does Egeria densa have on waterways?

    Are there any impacts to recreation and commercial activity?

    How does Egeria densa spread and how fast does it spread?

    How did Egeria densa enter the Delta?

    How much of the Delta is infested with Egeria densa?

    How can someone tell if the herbicide is working properly?


    • What is DBW's authority? Harbors and Navigation Code, Article 2, Section 64 provides that DBW is designated as the lead agency of the state for the purpose of cooperating with agencies of the United States and other public agencies in controlling water hyacinth and Egeria densa in the Sacramento-San Joaquin delta, its tributaries, and the Suisun marsh. State funding for controlling water hyacinth and Egeria densa is appropriated in California's annual Budget Act.
    • When did DBW begin treating Egeria densa? The Egeria densa program was authorized by law in 1997. Treatment for Egeria densa began in 2001.
    • Where does the funding for treatment of Egeria densa come from? Funding for the Egeria densa treatment comes from the Harbors and Watercraft Revolving Fund, which receives revenues from boaters' registration fees and gas taxes.


    For treatment, three permits are required to be obtained. These permits place restrictions on where and when DBW can treat the aquatic invasive weed (this varies throughout the Sacramento-San Joaquin Delta), establishes the chemical concentrations allowable in treated areas and requires extensive water quality monitoring.

    • Two permits are required by the federal Endangered Species Act from the United States Fish and Wildlife Service and the National Marine Fisheries Service (part of the National Oceanic and Atmospheric Administration).
    • A third permit, a National Pollutant Discharge Elimination System permit is required by the Central Valley Regional Water Quality Control Board.

    California Department of Parks and Recreation Division of Boating and Waterways will be conducting herbicide treatments in parts of the Sacramento-San Joaquin Delta to control Egeria densa and Curlyleaf Pondweed.

    The following information is subject to change based on governmental requirements, weather conditions, plant growth, waterway traffic, and other conditions.

    Proposed Treatment Period
    Starting March 10, 2016 through July 2016. Treatment period based upon DBW field survey data, water temperatures and fishery surveys.

    Potential Treatment Areas* (See map for treatment sites)
    In and/or around the following areas:

    • Anchorages, Boat Ramps and Marinas: Brannan Island State Recreation Area, Cruise Haven, Ox Bow Marina, Owl Harbor, Buckley Cove and Delta Marina.
    • Near Old River: Franks Tract (partial); Discovery Bay West; Holland Riverside; and Indian, Rock and Piper sloughs.
    • Stockton Area: Hog Island (Power Squadron), Westlake, Tinsley Island (St. Francis Yacht Club) and Fourteen Mile Slough (including Village West Marina).
    • Sacramento Area: Sycamore and Beaver sloughs.

    *Individual areas will be noticed prior to treatment application. If all listed sites are treated, acreage will total 2,273 acres.

    Herbicides Being Applied
    Fluridone - Registered for aquatic use with the U.S. Environmental Protection Agency and California Department of Pesticide Regulation.

    The public should not gather on or near boat docks during treatment applications. Boaters, swimmers, fisherman, and other recreationists in an area being immediately treated are urged to heed any directives aimed at protecting public safety offered by herbicide applicators.

    Treated areas will be monitored weekly to ensure herbicide levels do not exceed allowable limits, or have any significant adverse impacts on the environment, agriculture, or public health in or near the above mentioned treatment areas.

    Contact Information
    To report sightings or for more information regarding the control program, please visit DBW's website at, call (888) 326-2822 or email us at