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

Caboolture Water Quality Study
Table 1. Waterway attributes assessed in State of the Rivers Reporting (SoR, 2001)
Attribute
Reach environs
Channel habitat diversity
Stream bed and bank sediments
Bank Stability
Stream bed and bar stability
Riparian vegetation condition
Aquatic habitat
Water quality
Overall condition
Description
The extent of clearing, weed invasion in riparian vegetation, land
use, vegetation types and forms of disturbance.
Proportion of various channel habitats, reported as an index of
habitat diversity. Includes pools, riffles, backwaters, waterfalls,
glides and runs.
Sediment composition and size.
Proportion of the bank that is considered stable.
Density of bars and overall bed stability.
Proportion of cover and structure of riparian vegetation.
Proportion of stream bed covered by in-stream debris, rock
outcrops, vegetation, overhangs.
Odours, unnatural colours, forms, iron stains, discharge pipes,
slime and algae, water surface scum and oils.
Rating of all of the above attributes.
2.4.4 Land-use map, Caboolture Shire Council
CSC maintains a GIS-based land-use mapping system that records the spatial distribution of major
land-uses such as commercial, industrial, extractive resources, residential, rural, open space and state
forest (Figure 26, Appendix H).
3.0 WATER QUALITY GUIDELINES
Three categories of indicators were compared with guidelines to determine the condition of the
waterways: water quality indicators, sediment quality indicators, and faecal contamination indicators.
The guidelines used for each of these are discussed below.
3.1 Water Quality Guidelines
Water quality was assessed by comparing water quality at monitored sites with locally derived
reference values, as recommended in the Australian Water Quality Guidelines for Fresh and Marine
Waters (Australian and New Zealand Environment and Conservation Council & Agriculture and
Resource Management Council of Australia and New Zealand (ANZECC & ARMCANZ, 2000).
Reference values for an indicator are the measured values for that indicator at local reference sites,
that is, sites in local ecosystems that are in a substantially natural condition. Reference values provide
a reliable measure of natural water quality as they take local environmental conditions into
consideration. However, reference values do not in themselves represent water quality guidelines. To
determine an appropriate guideline, the degree of departure from “reference condition” (i.e. reference
values) that can be tolerated by the ecosystem needs to be determined. The National guidelines
(ANZECC & ARMCANZ, 2000) suggest that for physico-chemical indicators, the 20 th and 80 th
percentiles of the reference data should form the guidelines, and that the median value for indicators
at monitoring sites should fall within this range.
The Queensland EPA has developed water quality guidelines for Queensland (EPA, 2001) using the
approach recommended by the National Guidelines (ANZECC & ARMCANZ, 2000). The Queensland
guidelines are based on at least five years of monthly data, and are therefore unbiased with respect to
time. The geographic region of the reference sites is assessed to derive guidelines for southern,
central or northern regions of Queensland. In this study, the Southern Queensland Water Quality
Guidelines (EPA, 2001) were used. Guidelines are specified for several water types: ocean, open
coastal, enclosed coastal/lower estuary, mid estuary, upper estuary, lower catchment and upper
catchment.
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