Peel Inlet and Harvey Estuary System Management Strategy ...

EPA Report on the Peel-Harvey Progress and Compliance Report, 2003
8. THE DAWESVILLE CHANNEL, CATCHMENT
MANAGEMENT AND WATER QUALITY
The authors of the EPA Bulletin on the Peel-Harvey management strategy in 1988 were
farsighted in their advice on the requirements for a catchment management plan as an
integral part of the strategy for improving water quality. The management strategy
developed by the EPA in 1988 was the first attempt in Australia (and probably in the
world) at management of a diffuse source of pollution problem where catchment
management needed to be tackled in association with a major engineering approach. The
revised Environmental Protection Act was new in its application and the role of
Environmental Conditions in achieving management objectives identified by the EPA
was still being developed. Describing approaches and mechanisms for auditing
compliance by the Department and for proponents had barely commenced, and
environmental management systems were in their infancy. It was early days for
catchment management anywhere in Australia, and indeed the world.
The Peel-Harvey system was, and remains, an icon of Western Australia, as well as being
of international significance as a Ramsar wetland. The EPA 1988 assessment report
stated:
“Management of the problems of the Peel Inlet and Harvey Estuary waterways and their
catchments will require the adoption of a long-term view and a holistic approach.
Because some of the remedial measures proposed in this report will be on a scale and of
a kind not previously undertaken, they will generate considerable world-wide interest.
At the local level, the Dawesville Channel will be the largest coastal engineering
project undertaken since C Y O’Connor built Fremantle harbour. The proposals to
manage agricultural activities in the catchment would also be innovative in that the
emphasis is on a co-operative approach rather than on a strict regulatory approach of
the kind being adopted by a number of European countries to control similar problems
“ (EPA 1988, p. 1-2).
The Dawesville Channel
The Dawesville Channel has now been constructed and has been successful in improving
the water quality in the main body of the Peel Inlet and Harvey Estuary. However, water
quality and environmental problems remain in the rivers, and in areas such as the
Serpentine Lakes. The second part of the Strategy, that of catchment management to
“cap” the phosphorus input to the waterways remains the aspect of the management
package that still requires significant action.
The ERC report found that the predictions made by the EPA in regard to the channel’s
performance and likely environmental impacts were correctly predicted and no
unpredicted impacts resulted (see Table 7 of the ERC report). However, the success of
the Dawesville Channel in improving the water quality in the estuaries does not provide a
basis for any relaxation in the requirements for catchment management. The Channel has
an engineered, fixed maximum flushing capacity, and catchment management is essential
to provide an adequate buffer to ensure maintenance of the estuary health and resilience
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