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

Caboolture River Catchment
condition has remained fairly stable over recent years, although concentrations of oxidised nitrogen
have improved at the more downstream sites (WAR4,5,6).
The only site (WAR-2) to have an overall good water quality rating has also been found to have fish
communities that are classed as being in reference condition (Langdon, 2001). Other sites further
downstream, despite their poor water quality rating, had fish populations at moderate to sub-reference
conditions. The size of the riparian vegetation was good throughout Wararba Creek, although the
integrity was moderate to poor (Appendix G, ANA, 1998).
Two of the six sites monitored on Wararba Creek received good ratings for faecal coliforms, whereas
the other four received moderate ratings. Sorces of faecal contamination may include wild animals
and domestic stock.
5.1.4 Sheepstation Creek
Water quality at all sites in Sheepstation Creek was rated as being in moderate or poor condition, with
the more upstream sites being of poorer condition than the downstream sites. All sites had poor
dissolved oxygen levels, the upstream sites had high levels of turbidity and total phosphorous, and all
sites were rated as being in moderate condition for faecal coliforms. Analysis of changes in water
quality assessments over recent years indicated a reduction in concentrations of oxidised nitrogen and
total nitrogen at most sites, and a reduction in turbidity at downstream sites.
Concentrations of toxicants at two sites in Sheepstation Creek were good (below trigger levels) for all
toxicants, although lead concentrations were moderate at one site on one date, which may have
originated from roadways given this site is in an urbanised area.
Riparian vegetation, aquatic vegetation, reach environs and aquatic habitat are in poor or moderate
condition at downstream sites, whereas these attributes are in moderate to good condition further
upstream (SoR, 2001). Stream bed and bank stability have been classed as stable throughout
Sheepstation Creek, and fish communities at two sites in the middle reaches of the creek have been
classified as being degraded to severely degraded (SoR, 2001).
5.1.5 Lagoon Creek
Water quality at seven of the eight sites in Lagoon Creek was rated as poor; the remaining site
received a moderate rating. All sites had low concentrations of dissolved oxygen, with lowest levels
being recorded at the most downstream site. However, this site is a freshwater wetland and low
dissolved oxygen and pH could be expected due to the accumulation of organic matter and limited
water flow. Most sites also had high levels of turbidity and high concentrations of ammonia. Many sites
showed an improvement in concentrations of oxidised nitrogen and total nitrogen in recent years, and
some sites showed improvements in turbidity (Table 5). The regressions trend analysis also showed
that other sites have reduced in condition with regard to turbidity, and that some sites have
deteriorated with regard to dissolved oxygen and pH (Table 31).
Most biological and physical indicators such as fish, riparian vegetation, reach environs, bank stability
and bed and bar stability all increased in quality from downstream to upstream sites (Appendix, F, G;
SoR, 2001; Langdon, 2001). However, aquatic habitat was moderate at downstream sites and
decreased to poor at the more upstream sites; aquatic vegetation was poor throughout the creek
(SoR, 2001).
Sites LC6 and LC7 were had moderate concentrations of total petroleum hydrocarbons in the
sediments (Table 6), which may be a consequence of their proximity to highways and main roads of
the shire. Lead concentrations were moderate at one site on one occasion, and concentrations of all
other toxicants were good at all other sites (Table 6). Most sites received good condition ratings for
faecal coliforms, although sites LAG-5 and 6 received only moderate ratings.
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