Hawkesbury-Nepean River Environmental Monitoring Program
Hawkesbury-Nepean River Environmental Monitoring Program
Hawkesbury-Nepean River Environmental Monitoring Program
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Figure 6.35: Example of fine-scale historical comparison of the apparent change in<br />
distribution of Egeria densa near Richmond between surveys conducted in 2004 (top)<br />
and 2007 (bottom) (Thiebaud and Williams 2008)<br />
Water quantity and quality monitoring<br />
The <strong>Hawkesbury</strong>-<strong>Nepean</strong> <strong>River</strong> is relatively well serviced by river flow/level gauges<br />
and pluviometers, with data for some sites stretching back over 100 years. Recent<br />
trends in hydrology and water quality in the <strong>Hawkesbury</strong>-<strong>Nepean</strong> <strong>River</strong> need to be<br />
interpreted in terms of longer-term cycles (e.g. El Nino Southern Oscillation and<br />
Interdecadal Pacific Oscillation); in terms of major government initiatives under the<br />
Metropolitan Water Plan; and in terms of potential climate change effects in the<br />
future. Analysis of the data indicated that there has been a significant reduction in<br />
flows over Penrith Weir (and other areas), and river flow at Penrith weir remains<br />
much less than the long-term (>100-year) average. <strong>River</strong> regulation is not the sole<br />
factor involved in this decline, since similar declines are also noticeable in the flow<br />
66 <strong>Hawkesbury</strong> <strong>Nepean</strong> <strong>River</strong> <strong>Environmental</strong> <strong>Monitoring</strong> <strong>Program</strong>: Final Technical Report