Draft Proposals Paper - Full - Victorian Environmental Assessment ...

Levee banks
The third issue is levee banks for flood mitigation.
Throughout the Investigation area there are numerous
levee banks, used to manage or mitigate flooding, mostly
on private land but some also located on public land.
Many, including both those located on private and public
land are in need of major maintenance or upgrade to
remain effective. Many of these levee banks (such as along
the Old Mail Road in the Lindsay–Wallpolla area and in the
lower Goulburn River area) either impede water
movement across the floodplain or are in disrepair. Where
levees are in disrepair, there should be an assessment of
whether the structures are still required or in fact could be
removed or constructed in an alternative manner, thereby
achieving greater spatial coverage during flooding events.
Management of flooding at the boundaries of private and
public land could be managed without levees and
facilitate the greater floodplain connectivity through the
use of special area plans under the Catchment and Land
Protection Act 1994 and environmental overlays under the
Planning and Environment Act 1987.
Salt accumulation on the floodplains
The final issue is salt accumulation in the floodplain soils
where the groundwater is shallow. This salt accumulation
has increased as a result of shallower groundwater levels
from irrigation and native vegetation clearing. Tha salt
levels were kept in check naturally by flooding and rainfall
but with a decline in both the rate of salt accumulation in
the Lindsay-Wallpolla area has led to significant areas of
degraded vegetation. Salt accumulation coupled with lack
of flooding and drought conditions is showing visible signs
progressively up the River Murray.
Summary of environmental water issues
In summary VEAC believes that decision making processes
involved in determining environmental flow events for the
protection of the unique riverine ecosystems should be
undertaken in the context of the following framework.
Environmental flow allocations be determined in the
context of clearly stated ecological objectives at a regional
and River Murray scale and be informed by:
• an understanding of the natural water regimes with
respect to volume, seasonality, annual variability and
duration conditions
• ecosystem values and maintenance of those values
rather than the requirements for environmental
restoration works such as flushes for blue-green algae or
salinity management or to support public land resource
utilisation industries.
The arrangements or processes through which these
considerations are addressed should be:
• based on rigorous, transparent and scientifically based
methodology, including water accounting practices that
are freely available to the public
• flexible and adaptable to enable changes to be
introduced when increased information and
understanding becomes available and climate change
impacts require addressing
• based on a delivery system that is compatible with
ecological objectives and attempts to minimise energy
inputs or extensive infrastructure.
RECOMMENDATIONS
Environmental water
R10
R11
R12
R13
R14
R15
R16
R17
That the environmental outcomes for the Investigation sought through the public land category system are
dependent on a volume of water in the order of 4000 gigalitres for a floodplain inundation event at least
every five years.
That an Investigation area wide environmental flow strategy be developed with the objective of achieving
an integrated and consistent approach to environmental flows across the River Murray area, its Victorian
tributaries and the key wetlands of Kerang Lakes, Corop Wetlands, Boort Wetlands and Kanyapella Basin
described in Chapter 3.
That the improvement of the information and knowledge base of the River Red Gum forests and their
ecosystems and wetlands, hydrology and the river as a system, and in particular the use of models to
integrate this information, be given a high priority and for this information and knowledge be readily
available to the community.
That sufficient resources be allocated as a matter of highest priority for the development of a detailed
environmental water accounting system across the entire Investigation area.
That land and water managers develop a suite of non-engineering options to mitigate the causes of
summer flooding in Barmah forest.
That the relevant agency conducts an audit of existing levee banks in the Investigation area and where
appropriate remove those levees in disrepair or seek alternative structures to facilitate greater dispersal of
flood waters across floodplains; and where this is deemed necessary land and water management agencies
undertake an extensive consultation process with private land holders and relevant public land managers.
That where changes to water supply infrastructure are likely to occur in the future then environmental
flows should not be adversely affected and additional costs associated with the provision of environmental
flows be borne by the whole community.
That where potential opportunities exist, special area plans and the statutory planning processes be applied
as management tools to more effectively manage environmental flows for ecological outcomes at the
interface between public and private land.
14 River Red Gum Forests Investigation July 2007