2016-02-02 P&O Committee - Item 3 - Attachment 3 - Noosa River Environmental Values and Water Quality Objectives

Noosa River environmental values and water quality objectives



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Water area/type            Management              Water quality objectives to protect aquatic ecosystem EV
  (refer Plan             intent (level of
   WQ1401)                  protection)

Ground waters           Aquatic                  Where ground waters interact with surface waters, groundwater
                        ecosystem – high         quality should not compromise identified EVs and WQOs for those
                        ecological value         waters.

                                                 Note: the AWQG [2000] recommends that that the highest level of
                                                 protection should be provided to underground aquatic ecosystems,
                                                 given their high conservation value. Where ground waters are in
                                                                                                                    th
                                                 good condition the intent is to maintain existing water quality (20 ,
                                                    th       th
                                                 50 and 80 percentiles). There is insufficient information available
                                                 to establish current water quality for ground waters. Refer to
                                                 Appendix D in Queensland water quality guidelines for details on
                                                 how to establish a minimum water quality data set for deriving local
                                                    th   th       th
                                                 20 , 50 and 80 percentiles.
Wetlands                Aquatic                  Objectives as per AWQG (2000) and section 3.1.3.
                        ecosystem –
                        moderately
                        disturbed

Notes:
1.  Oxidised N = NO2 + NO3. Units for nitrogen indicators are micrograms per litre (µg/L) N.
2.  Units for phosphorus indicators are micrograms per litre (µg/L) P.
3.  n/d = no data, n/a = not applicable for this indicator and water type.
4.  DO objectives apply to daytime conditions. Lower values may occur at night but these should not be more than
    10%–15% less than daytime values. DO values as low as 40% may occur in estuaries for short periods following
    material inflow events after rainfall. DO values <50% are likely to significantly impact on the ongoing ability of fish to
    persist in a waterbody. DO values <30% saturation are toxic to some fish species. These DO values should be
    applied as absolute lower limit objectives for DO. – see also section 4.2 of the QWQG. Very high DO
    (supersaturation) values can be toxic to some fish as they cause gas bubble disease.
5.  DO values for freshwaters should only be applied to flowing waters. Stagnant pools in intermittent streams
    naturally experience values of DO below 50% saturation.
6.  Wallum/tannin-stained waters contain naturally high levels of humic acids (and have a characteristic brown ti-tree
    stain). In these types of waters, natural pH values may range from 3.6 to 6.
7.  During flood events or nil flow periods, pH values should not fall below 5.5 (except in wallum/tannin waters) or
    exceed 9.
8.  Nutrient objectives do not apply during high flow events. See QWQG Section 5 and Appendix D for more
    information on applying guidelines under high flow conditions.
9.  During periods of low flow and particularly in smaller creeks, build up of organic matter derived from natural sources
    (e.g. leaf litter) can result in increased organic N levels (generally in the range of 400 to 800µg/L). This may lead to
    total N values exceeding the WQOs. Provided that levels of inorganic N (i.e. NH3 + oxidised N) remain low, then
    the elevated levels of organic N should not be seen as a breach of the WQOs, provided this is due to natural
    causes.
10. Conductivity. Under natural conditions, conductivity is highly dependent on local geology and soil types. The
    Queensland Water Quality Guidelines 2009 (Appendix G) provides information on conductivity values in a set of 18
    defined salinity zones throughout Queensland. For each zone, the Queensland Water Quality Guidelines 2009
    provide a range of percentile values based on data from all the sites within that zone. This provides a useful first
    estimate of background conductivity within a zone. However, even within zones there is a degree of variation
    between streams and therefore the values for the zone would still need to be ground truthed against local values.
11. Temperature varies both daily and seasonally, it is depth dependent and is also highly site specific. It is therefore
    not possible to provide simple generic water quality objectives (WQOs) for this indicator. The recommended
    approach is that local WQOs be developed. Thus, WQOs for potentially impacted streams should be based on
    measurements from nearby streams that have similar morphology and which are thought not to be impacted by
    anthropogenic thermal influences.
    From an ecological effects perspective, the most important aspects of temperature are the daily maximum
    temperature and the daily variation in temperature. Therefore measurements of temperature should be designed to
    collect information on these indicators of temperature and, similarly, local WQOs should be expressed in terms of
    these indicators. Clearly, there will be an annual cycle in the values of these indicators and therefore a full
    seasonal cycle of measurements is required to develop guideline values.




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