Caboolture Region Water Quality Study - Moreton Bay Regional ...

Caboolture Water Quality Study
EXECUTIVE SUMMARY – WATER QUALITY CONDITION
Water quality data collected during three environmental monitoring programs since January 1999 was
collated and assessed to monitor the health of major waterways in Caboolture Shire. Data was
obtained from the Caboolture Shire Council’s Environmental Monitoring Program, the Environmental
Protection Agency and Ecological Health Monitoring Program (EHMP), and the Pumicestone Region
Coastal Monitoring Program (PRCMP). Indicators of water quality, sediment quality and faecal
contamination were used during assessments. Water quality was assessed by comparing values for
indicators at monitored sites with locally derived reference values (EPA, 2001), whereas guidelines for
sediment quality and faecal contamination were adopted from the National Guidelines (ANZECC &
ARMCANZ, 2000)
A synopsis of the water quality analysis for each waterway, and then for waterway health overall,
follows. Figure i shows the overall water quality assessments for all sites assessed for 2000-2001
period.
Sites in the estuarine reach of the Caboolture River had poor water quality, primarily caused by low
concentrations of dissolved oxygen, and high turbidity and nutrient concentrations. Above the tidal limit
in the freshwater reach, three of the five sites had good ratings. Water clarity, pH and salinity were
generally good throughout the river, although turbidity was elevated at some estuarine sites. Nutrient
(nitrogen and phosphorus) concentrations were elevated at most of the estuarine sites. Water quality
in the estuary was impacted by discharge from a major wastewater treatment plant, resulting in
increased nutrient loads and reduced levels of dissolved oxygen. Recent upgrades to the main
treatment plant are likely to lead to improvements in water quality throughout the estuarine reach of
the Caboolture River.
The majority of sites monitored in Wararba Creek were found to have poor water quality, although the
most upstream site had good water quality. All sites monitored had moderate to high concentrations of
total phosphorous and low dissolved oxygen and most had high concentrations of ammonia.
Overall water quality at all sites in Sheepstation Creek was in moderate to poor condition, with the
more upstream sites being in poorer condition than the downstream sites. All sites had low dissolved
oxygen levels, and upstream sites had high concentrations of total phosphorous and turbidity. Faecal
coliform contamination was moderate at all sites monitored. Concentrations of oxidised nitrogen, total
nitrogen and turbidity have improved in recent years. Concentrations of toxicants in sediments were
low.
Water quality at most sites in Lagoon Creek was rated as poor. All sites had poor condition ratings for
dissolved oxygen, and most sites had high concentrations of turbidity and ammonia and moderate
concentrations of oxidised nitrogen.
Overall water quality at sites along Burpengary Creek was poor. All sites had low dissolved oxygen
and high concentrations of total phosphorous. Downstream sites had high concentrations of ammonia.
Sites located adjacent to and downstream from the major area of urban development on the creek
were generally in worse condition than more upstream sites. Faecal contamination was not evident at
most sites, and moderate at two sites.
Saltwater Creek passes through the main industrial area of the Caboolture Shire and most sites had
poor water quality. Dissolved oxygen, turbidity, ammonia and total phosphorous concentrations
typically failed to meet the guideline values and median values of faecal coliforms were high at most
sites. Sediment quality was poor at sites within and adjacent to stormwater retention structures located
at a timber yard, and at a site adjacent to a stormwater outlet.
Water quality throughout Deception Bay was variable. Generally the sites closer to land had poorer
water quality than those further from land. Excluding conductivity (which is not a useful indicator in a
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