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

Saltwater Creek
Table 10. Water quality assessments for Saltwater creek, 2001. These ratings represent assessments based on water quality
data for the period October 2000 to September 2001. The dots indicate the latest water quality assessment in comparison to the
Queensland Water Quality Guidelines (green= good, yellow= moderate, red= poor, grey= insufficient data or median was
detection limit which was greater than the guidelines). The arrows indicate trends in median concentrations over the last 3
years. The colour of the arrow indicates whether the water quality has improved (green) or deteriorated (red), and the direction
of the arrow shows whether the median increased (up) or decreased (down). Double-ended arrows (black) indicate variable
trends.
Site
Water Type
Stream
Source
pH
Conductivity
Dissolved
Oxygen
Turbidity
Secchi Depth
Oxidised
Nitrogen
Ammonia
Total Nitrogen
Total
Phosphorous
Chlorophyll a
Organic N
FRP
FINAL
SAL-1 LC Saltwater Ck CSC
SAL-2 LC Saltwater Ck CSC
SAL-3 LC Saltwater Ck CSC
SAL-4 LC Saltwater Ck CSC
SAL-5 LC Saltwater Ck CSC
SAL-6 LC Saltwater Ck CSC
SAL-7 LC Saltwater Ck CSC
SAL-8 LC Saltwater Ck CSC
SAL-9 LC Saltwater Ck CSC
The retention structure site also had poor sediment quality, with arsenic, chromium, copper, nickel,
lead, zinc and mercury all above the ANZECC high trigger levels. In June 2000, the site adjacent to
this retention structure recorded sediment toxicant concentrations similar to those recorded within the
structure. In January 2001, the site upstream of the structure also recorded elevated sediment toxicant
levels. However, this site is located at a stormwater discharge pipe and many of these metals have
been previously linked to urban stormwater run-off (Moss and Costanzo, 1998). Both of these events
were not detected in later sampling (Table 10). Concentrations of mercury, lead and zinc at some of
the upstream sites were also found to be above the ANZECC low trigger levels
Fish and macro-invertebrate studies have reported mixed results for Saltwater Creek. Macroinvertebrate
investigations failed to indicate either good or poor water quality at all sites, other than at
one of the more upstream sites, which was in good ecological condition (SCCMAP, 1999). The most
abundant fish species at most sites was Gambusia holbrooki (mosquitofish), which is frequently
associated with poorer water quality and degraded stream habitat. Native gudgeons (Hypseleotris
spp.) dominated only one upstream site.
The upstream section of Saltwater Creek (SC1-8) had moderate riparian vegetation integrity and the
size was rated as good despite being situated in an industrial land-use area (Appendix G, ANA, 1998).
In the residential areas downstream of SC8, the size and integrity of riparian vegetation were both
good (Appendix G, ANA, 1998).
Median concentrations of faecal coliforms were high at all sites within Saltwater Creek, except for the
most upstream site (SAL-1; Table 11), which is located at the upstream margin of the industrial area.
All sites downstream of SAL-1 had elevated concentrations of faecal contamination, indicating
potential sources of faecal contamination from within the industrial area.
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