Hawkesbury-Nepean River Environmental Monitoring Program

4. Data received from agencies
Water quantity and water quality
The majority of water quality and hydrology data for the Hawkesbury-Nepean River
were provided to DECC by SCA and Sydney Water in January 2007. An update was
requested from SCA in August 2007 to bring the water quality and hydrology data up
to 30 June 2007 (or as close as possible to this date). Where there were multiple
records for water quality on the same day, the median of readings have been
calculated and included in all graphics and analyses. Some provisions for optimising
data quality and consistency have been made, but this has not fixed all the problems
that exist in the data; the results presented here assume that any further errors in
individual recordings have occurred essentially at random and have little effect on the
analyses.
SCA water quantity and water quality data were extracted from two main databases:
Hydsys/Hydstra for water quantity; and the SCA’s customized Water Quality
database (Oracle Software). SCA flow (level) data for many sites are measured at
15-minute intervals, however, for this study a daily flow rate was extracted and used
in subsequent analyses. Water quality is currently monitored (at most sites) on a 4weekly
basis, although the period between successive samples has varied over time,
particularly in earlier monitoring periods.
Sydney Water’s data were extracted from their Monitoring Service’s Water Quality
Data Warehouse. Water quality is monitored (at most sites) on a 4-weekly basis,
although the period between successive samples has also varied over time,
particularly in earlier monitoring periods. An exception to this is North Richmond (site
N42) where water is extracted for water supply purposes and water quality
monitoring is undertaken on a weekly basis. The differing frequencies of sampling
are an important point and can influence the period required for the detection of
trends.
Daily rainfall at Cataract Dam and southern oscillation index (SOI) data were
obtained from the Bureau of Meteorology website (http://www.bom.gov.au/ ).
Macroinvertebrate data
SCA macroinvertebrate data are currently collected in two main projects:
• the Woronora Environmental Flows project, which repeats (with some additions)
the sampling sites studied by Growns and Growns (2001)
• the Macroinvertebrate Monitoring Program (MMP), which samples a series of
fixed and random sites throughout the Hawkesbury-Nepean and Shoalhaven
catchments.
Sydney Water routinely monitors macroinvertebrates upstream and downstream of
its major STP outlets.
Relevant data from these programs were collated, checked for consistency and
combined into new datasets.
Algal and cyanobacterial data
Algal and cyanobacterial data were obtained from Sydney Water’s Monitoring Data
Warehouse and historical Algal Database. At many sites algal and cyanobacterial
counts are conducted only if chlorophyll-a levels are above 10 µg/L. This means that
much of the data collected are representative of relatively high algal conditions,
8 Hawkesbury Nepean River Environmental Monitoring Program: Final Technical Report