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FOR
IMMEDIATE RELEASE: Thursday,
September 30, 2004
Contact:
Rick Johnson, Weed Coordinator 786-5576
Noxious Weed
Invades the
Chehalis
River
in
Thurston
County
OLYMPIA
– First found growing in
Thurston
County
in the
Chehalis
River
in 1998, populations of the noxious weed Brazilian elodea have exploded over
the past two seasons.
More than 7,000 lbs of Brazilian elodea was
removed from the
Chehalis
River
July 19-July 29, by a contractor working for Thurston County Noxious Weed
Control.
Brazilian elodea is native to
South America
. It has been imported to
North America
, as well as many countries around the world, as an aquarium plant (often sold
under the name of Anacharis). Brazilian elodea is a submersed, freshwater
perennial. It roots in water up to
20 feet deep, with the stems growing up to the surface of the water, where
they form dense mats. Roots grow
from the stem nodes; leaves and stems are bright green.
The plant is spread by fragmentation. Brazilian elodea has four
(sometimes eight) leaves, while the native elodea, has three.
Dense stands affect water movement, water
quality, recreational uses, and navigation. The plant can also trap sediment
thereby impacting native plants and fish.
Brazilian elodea grows rapidly in the spring, shading out slower
growing native plants. It is illegal to sell this plant in the state of
Washington
.
Diver dredging
(suction dredging) was used on a one-mile stretch of the
Chehalis
River
in
Thurston
County
at mile 60. Diver dredging is a method where divers use hoses attached to
small dredges to vacuum plant material out of the river. This is primarily a
removal process following dislodging of the roots by divers.
The purpose of diver
dredging is to effectively remove all of the plant biomass including the
roots. The divers use the suction device for Egeria disposal only. The water
is returned back to the river and the plant material is then disposed of.
This project was
funded by the Washington Department of Natural Resources and administered
through the Thurston County Noxious Weed Control Department.
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