Division of Boating and Waterways to Begin Annual Control Efforts for Aquatic Invasive Plants in the Sacramento-San Joaquin Delta
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Newsroom@parks.ca.gov
SACRAMENTO – California State Parks’ Division of Boating and Waterways (DBW) announced today its 2025 control efforts for invasive aquatic plants in the Sacramento-San Joaquin Delta and its southern tributaries (Delta). Starting March 20, DBW will begin herbicide treatments on water hyacinth, South American spongeplant, Uruguay water primrose, alligator weed, Brazilian waterweed, curlyleaf pondweed, Eurasian watermilfoil, coontail, fanwort, and ribbon weed in the Delta. The treatment start date may change depending on weather conditions and plant growth/movement.
“DBW continues to work with the public and our local, state and federal partners to control these aquatic invasive plants to reduce or eliminate the negative impacts on people’s daily lives and businesses,” said DBW’s Deputy Director Ramona Fernandez. “The continued use of monitoring and technology allows the division to focus on the areas that best help us manage the challenges.”
These aquatic invasive plants have no known natural controls in the Delta, the West Coast’s largest estuary. They negatively affect the Delta’s ecosystem as they displace native plants that are essential to the area’s biodiversity while negatively impacting the economy, environment and public health. Continued warm temperatures help the plants proliferate at high rates. Plants are also known to form dense mats of vegetation, creating safety hazards for boaters and obstructing navigation channels, marinas, and irrigation systems. Due to their ability to spread rapidly to new areas, the plants will likely never be eradicated from Delta waters. Therefore, DBW operates control programs as opposed to eradication programs. The division works with local, state, and federal entities to better understand the plants and implement new integrated control strategies to increase efficacy.
Funding for DBW’s aquatic invasive plant control programs comes from the Harbors and Watercraft Revolving Fund, which receives revenues from boaters’ registration fees and gasoline taxes.
All herbicides are registered for aquatic use with the U.S. Environmental Protection Agency and the California Department of Pesticide Regulation. Treated areas for submersed aquatic vegetation (Brazilian waterweed, curlyleaf pondweed, Eurasian watermilfoil, coontail, fanwort, and ribbon weed) will be monitored to ensure herbicide levels do not exceed allowable limits and follow EPA-registered label guidelines. The public may view the public notices and sign up to receive weekly updates on this year’s treatment season on DBW's website. Below is a list of proposed control actions for the 2025 treatment season:
Floating Aquatic Vegetation Control Program
Water hyacinth, South American spongeplant, Uruguay water primrose, and alligator weed.
Herbicide Control:
- Treatment Period: All sites March 20, 2025 –Nov. 30, 2025
- Type of Herbicides: Glyphosate, Imazamox, 2,4-D, or Diquat
- Potential Treatment Areas: Initially in and/or around but not limited to the following areas: San Joaquin River, Old River, Middle River, Fourteen Mile Slough, and Snodgrass Slough.
Submersed Aquatic Vegetation Control Program
Brazilian Waterweed, curlyleaf pondweed, Eurasian watermilfoil, coontail, ribbon weed, and fanwort.
Herbicide Control:
- Treatment Period: Starting March 20,2025, through November 30, 2025, treatment period based upon DBW field survey data, water temperatures and fish surveys.
- Type of Herbicide: Fluridone, Diquat, or Endothall.
- Potential Treatment Areas: In and/or around the following areas (individual areas will be noticed prior to treatment application)
- Anchorages, boat ramps and marinas: B & W Resort, Delta Marina Yacht Harbor, Grindstone Joes, Hidden Harbor Resort, Korth’s Pirates Lair, Oxbow Marina, Owl Harbor, River Point Landing, Rivers End, St. Francis Yacht Club, Tiki Lagoon, Tracy Oasis Marina, Turner Cut Resort, Vieira’s Resort, Village West Marina, and Willow Berm.
- Near Old River: Berkeley Ski Club, Bullfrog Ski Club, Cruiser Haven, Delta Coves, Diablo Ski Club, Discovery Bay, Golden Gate Ski Club, Stockton Ski Club, Piper Slough, Sandmound Slough, Taylor Slough, Orwood Marina, Italian Slough, Hammer Island, and Kings Island.
- Sacramento Area: French Island, Hogback, Long Island Slough, Sacramento Marina, Snug Harbor, and Washington Lake.
- Stockton Area: Atherton Cove, Calaveras River, Bishop Cut, Honker Cut, Mosher Slough, Stockton Sailing Club, and Windmill Cove.
- Antioch Area: Lauritzen Yacht Harbor, and New Bridge Marina.
Last year, DBW treated 2,649 acres of floating aquatic vegetation and 1,115 acres of submersed aquatic vegetation. No mechanical harvesting was conducted. A combination of herbicide, biological and mechanical control methods will be used to help control invasive plants at high-priority sites in the Delta.
In 1982, California state legislation designated DBW as the lead state agency to cooperate with other state, local and federal agencies in controlling water hyacinth in the Delta, its tributaries, and the Suisun Marsh. The Egeria Densa Control Program was authorized by law in 1997 and treatment began in 2001. In 2012, spongeplant was authorized for control upon completion of the biological assessment. In 2013, DBW’s jurisdiction expanded to include other invasive aquatic plants, and since then other aquatic invasive plants such as Uruguay water primrose, Eurasian watermilfoil, Carolina fanwort, coontail, alligator weed, and ribbon weed have been added to the AIPCP program.
To report sightings, subscribe for program updates or for more information regarding the control program, connect with us online at dbw.parks.ca.gov/AIS, via email at AIS@parks.ca.gov or by phone (888) 326-2822.
Photos from Division of Boating and Waterways.
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