Attachments 11.4 and 11.5 - City of Busselton

ATTACHMENT C - TREATMENT OPTIONS CONSIDERED IN THE COUNCILLOR WORKSHOP OF MAY 2011
ITEM 11.4 COUNCIL 12/10/2011
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conditions of high turbidity and phytoplankton (Novak and Chambers 2005;
Paice, 2009). V. australis grown in a meadow situation was found to
substantially increase aquatic invertebrate abundance and diversity, and
sustain a more consistent zooplankton population (Paice, 2009).
In terms of water quality, the meadow trials in 2007-08 were too small to
determine any measurable improvement. However the meadows did appear
to trap particulate materials, indicating increased sedimentation and reduced
re-suspension which could potentially contribute to improved water quality
(Paice, 2009). A larger macrophyte meadow was established in 2009
upstream of the Busselton Bypass, and water quality monitoring has
indicated lower phosphorus concentrations and lower turbidity in the
meadow compared to adjacent open waters (Murdoch University,
unpublished data).
A new project is proposed to investigate whether macrophytes that tolerate
high nutrient and low light conditions can be used to reinstate a macrophyte
dominant regime. It will examine whether such established macrophyte beds
coexist with algal blooms or whether, by the mechanisms outlined above,
the macrophyte reduces phytoplankton growth and/or nutrient status of the
water.
Macrophytes have the potential to improve water quality, as well as
enhance ecological function, however it is a new technique which is best
undertaken as a restoration and research project. The attached report
(Attachment A) provides a draft outline for a combined research and
restoration project in the Lower Vasse River that would result in both direct
action in the Lower Vasse River and important research outcomes. It is a
basis for discussion and project development. This macrophyte project is
recommended for support by Council.
Enzymes
Enzymes are chemicals that occur in nature and include complex strands of
protein that accelerate certain reactions. Enzymes will target different
substrates in the water and bond with them, subsequently reducing them on
a molecular level. Through this reaction they form harmless compounds that
will have no further negative effect on the water. While enzymes are
chemicals, they are comprised of commonly occurring amino acids and can
be produced by certain bacteria. As they are chemical in nature, enzymes
will not reproduce after being introduced to the water. So they are a single
use product. The enzyme concentration in the water also stimulates any
bacteria present to speed the biological degradation.
One product, Soil-Zyme that has been used in large water bodies, in
conjunction with AirDuck aerators to improve mixing, has been promoted to
the Shire for use in the Vasse River. It is supposed to produce an 80% or
more reduction of algae and algae blooms, eliminating Blue-green algae
within 3-4 Days of application. A number of lakes are supposed to have
been shown to have no further outbreaks after using the product.