Sustainable Water Management Plan - Nillumbik Shire Council

Good stormwater quality is important as waterways
are integral to Nillumbik’s character, flora and faunal
biodiversity, as well as playing an important role in
influencing the wellbeing of the local community.
Many people use and enjoy the areas of open space
along waterways for various recreational activities,
and the degradation of these areas may ultimately
affect the quality of life enjoyed by the community.
Erosion and sediment control
Sediment in waterways can impact on plant growth
as well as the health of aquatic and fauna species
reliant on these water sources for habitat. Particles
of soil and silt can line the banks of waterways
smothering stream and riparian vegetation, while
heavy loads may also reduce the amount of oxygen
available to support aquatic life.
In addition to being important for social wellbeing,
stormwater is also a resource that can bring
environmental and economic benefits. Rather
than contributing to pollution, it can be captured,
treated and reused, becoming a major contributor
to our water supply. ‘Stormwater runoff from cities
is almost equal to the amount of potable imported
water that is used. More than 50% of high quality
drinking water piped to urban areas is used for
lower quality purposes such as gardening and
toilet flushing.’ Therefore there is great potential
to expand the reuse of stormwater for non-drinking
purposes. Conserving stormwater will also reduce
the level of pollutants reaching our local waterways.
Current water quality issues in Nillumbik
As part of Milestone 1 of the ICLEI Water Campaign,
Council undertook an inventory of water quality
within the municipality. This, in conjunction with a
review of the SMP and DWMP, highlighted some
gaps in the strategic management of Council’s
operations and responsibilities, which may negatively
impact on water quality. In particular, it identified
the three functions of Council which may have an
impact on water quality. These are erosion and
sediment pollution, wastewater treatment as well as
swimming pool management. Within the community
sector, activities also included erosion and sediment
pollution and wastewater treatment plus high levels
of nutrients and toxic pollutants. While not identified
as a major threat at present, gross litter levels
resulting from an increase in residential, industrial
and commercial development in the Shire should
also be considered as a management issue.
The Shire consists largely of rural and low density
residential zones with a number of small townships.
A large number of roads in these areas are unsealed
(dirt or gravel) and require regular regrading. Due to
the highly dispersive clay profiles during heavy rain
events, sediment from these roads can be washed
into stormwater drains and directed into local
waterways.
Although there is a minimal amount of development
occurring within the Shire, construction site run-off
(often a result of poor site management practices)
can lead to high levels of sediment and potentially
toxic materials being washed into local waterways.
Increasing urban development contributes to an
increase in stormwater run-off from impervious
surfaces that would have previously been absorbed
into the soil. In heavy rain, this results in higher
stream flows which can cause erosion of stream
banks resulting in loss of riparian habitat and
increased sediment pollution.
In some rural and low density residential areas, tree
and vegetation cover has been removed or degraded
due to poor stock management and land clearing
leaving creek and gully banks vulnerable to erosion.
Large infestations of rabbits and weeds are also
contributing to decreased bank stability and erosion
problems.
Wastewater treatment
It has been highlighted in both the SMP and DWMP
that there is a high risk to public health and the
environment from the use of domestic wastewater
treatment (or septic) systems in the Shire. A large
number of these systems, particularly those in
residential areas, are failing to deliver satisfactory
performance due to inappropriate system design
and/or management. While the management of
septics is the responsibility of the property owner or
resident, Council is responsible for ensuring these
systems do not cause a risk to public health or
the environment. Council is required to ensure the
appropriate selection and installation of septics on
private property and to monitor the compliance of
satisfactory system performance.
There is a large number of properties within the
Shire that currently discharge greywater off-site, a
consequence of previous environmental legislation
standards when it was assumed that properties
would be provided with reticulated sewerage
services within a short time frame. While many of
these properties are in areas currently listed on
the Yarra Valley Water sewerage backlog program,
at the time of this report timelines for sewerage
installation in these areas is still unknown and
uncertain. Some of these properties are in urban
parts of the Shire, but the true extent of the problem
is not fully known.
Many of the existing domestic wastewater treatment
systems throughout the Shire are not being
managed or maintained correctly. A survey of
residents undertaken by Council’s Public Health Unit
in 2005 identified that approximately 20% of systems
did not have the required servicing undertaken in
the appropriate timeframe. Surveys, discussions
with committees and property inspections have
identified that many property owners are unclear
of the requirements of septic system management
and, in some cases residents, are unaware that their
property is actually connected to a septic system.
The supply of reticulated water to properties which
are currently serviced by septics is also contributing
to septic management problems. When households
rely solely on rainwater, there is often a much
greater consciousness to reduce water usage. When
connected to reticulated water, limitations of water
use are not an obvious issue and occupants can be
less conscientious with water conservation. High
water use levels in the home can create pressures
on septic systems which are not designed to treat
large volumes of water.
Badly designed stormwater disposal systems
on properties in unsewered areas can affect the
placement of septic systems when developing new
properties. An integrated approach that considers
both stormwater and domestic wastewater treatment
and disposal needs to be undertaken when issuing
planning permits.
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