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

Pumicestone Passage
Figure 14. Box plots of results for conductivity in sites in Pumicestone Passage
Figure 15. Box plots of results for secchi depth for sites in Pumicestone Passage
Many sites have moderate or poor turbidity and/or secchi depth, and analysis of changes in water
quality assessment for these indicators suggest that they have deteriorated over recent years (Table
16, 23). The regression analysis of long-term trends indicated many improving and some deteriorating
trends at many sites within the Passage (Table 31, Appendix F). For example, dissolved oxygen and
secchi depth showed significant improvements at many sites (Pum-b, c, d, e, f, g, h, i, l, m), and
nutrients improved at Pum-d (ammonia by 16% per year and FRP by 10% per year), which is in the
northern Passage between the Bells and Coochin Creek mouths. At Pum-k, in the southern Passage
between Elimbah and Ningi Creek mouths, ammonia showed significant improvements (~25%
annually), although organic nitrogen concentrations increased (~10% annually)(Table 31)
.
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