Hawkesbury-Nepean River Environmental Monitoring Program

• Two species of weeds, Gymnocoronis spilanthoides and Sagittaria graminea ssp.
platyphylla, each with an emergent lifestyle, were present in limited amounts in
the central portion of the study area.
• The native submerged species Vallisneria gigantea was present throughout the
study area.
• Reaches 21, 22 and 23 (Wilberforce to Fairlight Gorge) have the greatest number
of exotic species of all three major groups, and they also have the greatest
number of native species. This part of the river is where most action for control of
exotic floating and submerged species has taken place in the past and should
continue into the future.
• The abundance of Egeria, and possibly some other species, was markedly
influenced by the minor flooding that occurred in the winter of 2007.
DPI Fisheries sampling in 2004 and 2007 has revealed that Egeria appears to have
expanded its range in recent times, particularly in the reach around Richmond and
Windsor (Figure 6.35).
7. Conclusions
Monitoring context
Cumulative development and population growth in the Sydney region and
catchments have placed the Hawkesbury-Nepean River system under increasing
pressure. The 2006 Metropolitan Water Plan sets out how the NSW Government will
provide a secure supply of water that can meet the long-term needs of Sydney. The
2006 Metropolitan Water Plan aims to ensure that there is:
• sufficient water available over time to meet the needs of a growing city and to
protect river health
• the ability to withstand current and future droughts, and impacts from climate
change.
The Hawkesbury-Nepean Environmental Monitoring Program will help in the longterm
monitoring and evaluation of the Metropolitan Water Plan. It will provide
information on broad-scale trends in river water quality (including nutrients, turbidity
and conductivity) and stream flows, as well as the biological patterns of the river’s
ecosystem (including invertebrates, fish and water plants). Evidence of trends will
guide future decisions and help assess the effectiveness of environmental flow
releases and other changes (NSW Government 2007). This report aims to identify
the current direction of water quality, quantity and ecosystem trends, and to provide a
benchmark for future monitoring as various initiatives under the Metropolitan Water
Plan roll out.
Hawkesbury Nepean River Environmental Monitoring Program: Final Technical Report 65