Dealing with salinity in Wheatbelt Valleys - Department of Water

Wallace
Australia by Agriculture Western Australia et al.
(1996a).
Toolibin Lake is listed on the Register of the National
Estate and under the Ramsar Convention as a
Wetland of International Importance. It is also
recognised as a threatened ecological community
under a State classification system (non-statutory),
and as a recovery catchment for natural diversity
under the Western Australian Salinity Action Plan
(Agriculture Western Australia et al. 1996b).
Recognition of the Lake’s importance as a recovery
catchment provides extra State resources for its
management. The values of the Lake are more fully
described in the Toolibin Lake Recovery Plan
(Toolibin Lake Recovery Team and Toolibin Lake
Technical Advisory Group, 1994).
HISTORY OF MANAGEMENT
Clearing of native vegetation began in the catchment
during the 1890s, and large areas had been cleared
by 1930. Following World War II clearing greatly
expanded and by 1996 only 14.6% of the original
native vegetation remained (Baxter & Bicknell 1996).
Much of this is degraded, and only 3% of the
catchment lies within nature reserves.
As a result of deep-rooted, perennial native
vegetation being replaced by annual crops and
pastures, recharge to groundwater increased. This in
turn has caused rising, highly saline groundwaters to
detrimentally affect plant growth as waters near the
land surface. In worst-affected areas, healthy surface
soils and waters become highly saline and only the
most salt tolerant species survive, or bare salt pans
develop. Salinisation results from both the direct and
indirect effects of rising groundwaters.
Direct effects occur when highly saline groundwaters
rise into the root zone of vegetation with aerial parts
(such as trees, shrubs and grasses) and kill them and
soil animals and plants. As salts reach the soil surface
they crystallise in surface soils, or pollute surface
waters. Indirect effects from salinity occur as surface
flows, generally between late autumn and late spring,
transport these salts to other areas that in turn
become increasingly saline. These processes have
dramatically changed many habitats, particularly
those on valley floors. Aquatic plants and animals
dependent on freshwater habitats and fringes have
been most affected. Apart from those species that
can use farm dams and ephemeral freshwater pools,
such as those on granite outcrops, freshwater life has
all but disappeared from the Wheatbelt.
– 2 –
Additionally, the volume of surface water flows have
increased as a consequence of clearing native
vegetation. Waterlogging and inundation have thus
combined with increasing salinity to cause
widespread death of native vegetation and their
associated fauna, loss of freshwater wetlands, and
loss of productive farmland. See chapters in Hobbs
& Saunders (1993) for a more detailed explanation of
these changes.
During the 1950s and 1960s wetlands downstream
of Toolibin became saline, and by the 1970s there
was considerable community concern that Toolibin
would soon follow. In response to this concern a
committee of State Government agencies was
formed in the late 1970s to study the Lake’s
problems and their solutions. The results of the
ensuing research are described in a report by the
Northern Arthur River Wetlands Committee (1987).
In the early 1980s, local farmers, concerned by
increasing loss of agricultural lands to salinity, formed
a Shire Land Conservation District Committee.
Later a specific Toolibin Lake Catchment Committee
was formed. Later again, a Recovery Plan + for the
Lake was produced for CALM by consultants
Bowman Bishaw Gorham et al. (1992), and this was
further developed by the Toolibin Lake Recovery
Team and Technical Advisory Group (1994). Blyth et
al. (1996) have described the history of these groups
in more detail.
In general terms, farmers and the Lake Toolibin
Catchment Group are primarily concerned with
management of freehold land, and CALM is
responsible for management of Toolibin Lake with
advice and guidance from the Recovery Team and its
associated Technical Advisory Group.
PHILOSOPHY
There is no single, consistent philosophy driving
work to recover Toolibin Lake and its catchment.
Rather, people and groups with differing philosophies
and goals are working together to implement actions
that will further their individual interests. These
individual interests are united and directed by a set of
points upon which all participants tacitly agree.
These are that:
+ Recovery is defined here as “the process by which the
decline of an endangered species, group of species, ecological
community or ecosystem is arrested or reversed, and threats
to its survival are neutralised so that its long term survival in
nature can be assured” (Endangered Species Unit 1991).