Agriculture and rivers and streams
Agricultural activities have changed much of the South Australian
landscape. Previously rich and abundant native vegetation has
been cleared to make way for crops and grazing land needed to
produce food products and textiles. An unfortunate consequence
of this agricultural development is that many of our river systems
have become degraded.
What problems does agriculture create for
our watercourses?
Agricultural activities have affected rivers and streams through
various processes.
Increasing salinity
Clearing native vegetation has raised the water table in many
parts of the state and consequently the soils and watercourses
in many areas have become increasingly saline. >>
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Reduced environmental flows
The use of water for irrigation has put pressure on rivers and
streams because of reduced environmental flows. This has been
particularly significant for the River Murray.
Increasing nutrients and turbidity
Many crops rely on the addition of fertilisers to promote rapid
growth. Fertilisers usually contain readily soluble nitrogen and
phosphorus compounds. The problem is that some of these fertilisers
are washed off the land or through the soil to surface water bodies
where they can create too much algal growth. >>
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Livestock access to rivers and streams can also introduce nutrients
as well as cause excessive bank erosion and increase the turbidity
(i.e. cloudiness) of the water.
Pesticides
Pesticides used in agricultural regions can be washed into rivers
and streams after rain. Some pesticides are persistent and can
be detected in water long after use. In South Australia pesticides
have been found in waterways and groundwater, and historical contamination
of soil is common around cattle and sheep dip sites. Pesticides
have caused fish and aquatic invertebrate kills in inland and
estuarine waters. Bird deaths have been attributed to pesticides,
and spraying to kill locusts has been shown to affect other organisms.
What is happening to reduce the impacts
of agriculture on rivers and streams?
The State Natural Resource Management (NRM) Plan 2005-10 is the
main impetus for the improving the health of rivers and streams
in South Australia while maintaining economic and social development.
The State NRM Plan is being administered through the Regional
NRM Boards. >>
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Catchment Water Management Boards (CWMBs) have been officially
replaced by NRM
Boards, although several Catchment Management Plans (produced
by the CWMBs) are still current and these provide strategies for
reducing the impacts of agricultural activities on rivers and
streams.
Primary Industries and Resources SA can provide useful advice
on environmentally responsible irrigation.
The EPA has released a series of guidelines to advise on responsible
agricultural practices. These include:
EPA Guidelines for Responsible
Pesticide Use (870KB PDF) are also available.
These bring together all the requirements that regulate the responsible
use of pesticides. These requirements are contained in the several
pieces of state and federal legislation. They include pesticide
registration and labelling, licensing of pest controllers and
commercial sprayers, dangerous substances administration and occupational
health and safety requirements.
Two guidelines that address the practical issues of pesticide
application have also been produced. These will be available for
downloading soon:
- Pesticide use by rural lifestyle landholders
- Commercial spray operator guideline
Water quality monitoring
The EPA ambient water quality monitoring program includes many
rivers and streams in agricultural regions. We monitor the concentrations
of nutrients in the water to determine how much is entering our
rivers and streams. We also monitor the aquatic ecological health
to determine if these nutrients are impacting on ecosystems. >>
More
>> direct to water quality data
Links
Natural Resource
Management Boards
This page was last modified 14-10-2008
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