found to be effective, in part because it is negatively buoyant.
It is imper
and
requires venting , and 'it is expensive (inflation-corrected
Polyvinyl also tended to crumple and was
1984, the price was ,194 ha-l).
easily dislodged by waves (Armour, Brown, and
1979).
Burlap (10 oz
was found by Jones and Cooke (1984) to be effective
for one season in an Ohio reservoir, but the material rotted even when treated
Despite the permeability of burlap, it ballooned,
a preservative.
gesting that the pores may have been clogged with organic matter and the asso-
and Trvelson (1984) report control of
ciated microbial community.
Eurasian watermilfoil with burlap for two or three growing seasons in British
Despite its
buoyancy, burlap must be securely
Columbia lakes.
Cost of burlap according to Jones and Cooke (1984) is about
anchored.
,400
Sediment covers, while very effective in eliminating problems with
rooted aquatic plants, cannot usually be used over large areas due to
A
to 40-ha treatment with Dartek would cost over 0,000 plus
costs.
However, smaller areas, such as docks and marinas, could be
installation.
In most cases, this would be an appropriate use
treated at a much lower cost.
of sediment covers.
Reservoirs often receive substantial silt loads, and waves may further
increase the quantity
suspended solids that could settle on the covers.
This problem could limit the longevity of
by sediment covers since
plant fragments may root in the deposited silt.
and Trvelson (1984)
report that a fabric called Texel, a negatively buoyant, needle-punched,
polyester fabric, may be particularly applicable to this situation because
fragments of plants appear to have difficulty in attaching to the upper
face and in penetrating the fabric.
In many cases, the reservoir manager will
have to be aware that sediment screens will require periodic cleaning and
repositioning to prevent new plant growth.
Several candidate materials are available, as reviewed earlier.
Feasi-
bility in reservoirs depends not only costs and the possibility of plant
regrowth on deposited sediments, but also the effectiveness and ease of appli-
cation.
An
evaluation of this should be conducted prior to full-scale
application to a particular area.
Ease of application, longevity of mate-
rials, and duration of control should be eval.uated for several types of sed-
iment covers.
Previous Page
