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For Immediate Release: 2/17/2015

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Herbicide Control of Egeria densa to Begin in the Delta in early March

Vicky Waters,

SACRAMENTO, Calif. – The California State Parks Division of Boating and Waterways (DBW) will begin its 2015 Egeria densa Control Program (EDCP) on March 9 in various areas of the Sacramento-San Joaquin Delta.  This year, curly leaf pondweed, another aquatic invasive weed, will be treated concurrently with Egeria densa (Brazilian Elodea) with the herbicide Fluridone.  All selected areas will be treated once a week for 12 continuous weeks. Treatment is subject to change based on governmental requirements, weather conditions, plant growth, waterway traffic and other conditions.

Treated areas will be monitored weekly to ensure herbicide levels do not exceed allowable limits, and that herbicide treatments have no adverse impacts on the environment, agriculture or public health in or near these planned treatment areas:


  • Kings Island Area:  Bishop Cut and Honker Cut


  • Anchorages, Boat Ramps and Marinas:  Korth Pirate’s Lair, Perry’s Yacht Harbor, BW Marina, Willow Berm Marina, Brannon Island State Park and Delta Marina


  • Contra Costa County:  Discovery Bay, Sandmound Slough, Dutch Slough, Taylor Slough, Piper Slough, Italian Slough, Holland/Riverside area and Kings Island


  • San Joaquin  County:  Atherton Cove/Louis Park, St. Francis Yacht Club, Hog Island (Power Squadron) and Fourteen Mile Slough (including Village West Marina)


  • Sacramento County:  Sacramento Marina, Sycamore Slough, and Beaver Slough

Sites were selected using both physical observation and underwater vegetation mapping techniques.   Rake samples were also taken to determine the dominant species of underwater vegetation. Site selection was made based on the amount of vegetation found, recreational use of the area, propeller clearances and whether the vegetation was a hazard to navigation.

The EDCP was established in 2001 to control Egeria densa in the Delta and its major tributaries. The program is managed by DBW with its federal partner, United States Department of Agriculture, Agricultural Research Service. This is the first year curly leaf pondweed is treated by DBW. Egeria densa begins to show symptoms of herbicide treatment approximately three to four weeks after the first treatment. Bleaching of plant tips is one symptom. This bleaching continues down the stem of the plant eventually killing the plant. 

Egeria densa is a fast growing, non-native submerged aquatic plant having a significant impact on the shallow water habitat in the Sacramento-San Joaquin River Delta ecosystem. In the 50 years since the plant was introduced into the Delta, the infestation has grown to approximately 10,000 surface acres or 18 percent of 55,000 surface acres of the Delta. It is important to note that this plant has never been eradicated from moving water anywhere in the world. Curly leaf pondweed is an invasive aquatic plant native to Eurasia.  This plant has become a problem within the Delta.  The Delta is conducive to growth of the curly leaf pondweed as this species tolerates low light and temperatures, prefers high nutrient waters and grows in shallow or deep water.

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