The Jefferson County Conservation District sponsored a demonstration day of aquatic plant
control methods in Lake Leland on September 11, 1998. Lake Leland is located in the
foothills of the Olympia Mountains in eastern Jefferson County five miles north of
Quilcene, Washington. The south end of this lake is heavily infested with a non-native
aquatic plant - Brazilian elodea (Egeria densa). The demonstration day was
planned to show lake residents some management activities that they could perform to help
manage the excessive growth of this noxious weed in Lake Leland. As part of the day's
activities, a bottom screen (also called bottom barrier) was installed at the dock of
local residents (with an appropriate permit from the Washington Department of Fish and
Wildlife).
 The
screen was constructed by home owners using heavy tarp material held in shape and
reinforced with PVC piping. It was weighted with steel rebar. This structure proved to be
too flexible to move easily and long lengths of aluminum piping were temporarily used to
strengthen the structure. After installation, the aluminum piping was removed. The picture
to the left shows the bottom screen on the lawn where it was constructed.
Click on each thumbnail photo to see the details.
 Luckily a
number of people showed up for the demonstration day because the bottom screen was
unwieldy. It required about ten people to lift and move the screen onto the dock prior to
slipping it into the water. The thumbnail photo on the right shows volunteers getting
 underneath and
starting to lift the screen. When the volunteers were in place, the screen was
"walked" onto the dock (photo on the left). Once on the dock,
 the screen
was set down while everybody discussed the best way to go about getting it into the water
(right). The plan was to install the screen immediately in front of the dock. The day
before, Jefferson County Conservation District employees and lake residents had cut and
removed most of the Brazilian elodea plants growing in this area. Before cutting, these
plants formed a mat on the water's surface. Cutting the plants prior to bottom screen
installation served two purposes (1) to facilitate lowering the screen into the water and
(2) to remove plant biomass to cut down on the amount of gasses produced by decomposing
plants.
As the time came to lower the screen into the water, two boats were stationed on either
side of the dock (left).
 Two large
innertubes were also positioned at each side of the dock. The leading edge of the bottom
screen was carefully lowered onto the inner tubes. The action of the the people pushing
the screen into the water and the guidance of the boaters facilitated the smooth movement
of the screen into the water and into the proper position. Despite some misgivings,
everything went well.
The boaters ensured that the bottom screen remained correctly in place as it slowly
sank to the bottom of the lake
 (right). The
installation went surprisingly well considering that the bottom screen was unwieldy.
However, without the efforts of many neighbors, it would have been extremely difficult for
this screen to have been installed. Installing this screen is a good example of home
owners working cooperatively to manage aquatic weeds around a dock.
Find out how you can construct and install
a bottom screen!
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Rolling | Aquatic Herbicides
| Biological Control
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Questions about
this page?
Contact Kathy Hamel by e-mail at kham461@ecy.wa.gov Last
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