deriving local water quality guidelines - environment

Guideline

Environmental Protection (Water) Policy 2009

Deciding aquatic ecosystem indicators and local water quality guidelines

December 2018

Prepared by: Environmental Policy and Planning Division, Department of Environment and Science.

© State of Queensland, 2018.

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Contents 1 Introduction ............................................................................................................................................................ 4

1.1 This guideline ................................................................................................................................................ 4

1.2 Background ................................................................................................................................................... 4

1.3 Key terms ...................................................................................................................................................... 5

2 Deriving local water quality guidelines that protect the aquatic ecosystem environmental value ......................... 7

2.1 Levels of aquatic ecosystem protection ........................................................................................................ 7

2.2. Indicators and water quality guidelines for environmental values ................................................................ 8

2.3. Spatial definition of waters, water types and management intent ................................................................ 8

2.4 General approaches for deriving local water quality guidelines for aquatic ecosystems ............................. 8

2.4.1 Using ecological effects data ........................................................................................................................ 9

2.4.2 Using reference site data ............................................................................................................................. 9

2.5 Deriving local water quality guidelines and comparison of test site data with guidelines/objectives ........... 9

2.5.1 High ecological value (HEV) waters ........................................................................................................... 10

2.5.2 Slightly disturbed (SD) waters .................................................................................................................... 11

2.5.3 Moderately disturbed (MD) waters ............................................................................................................. 12

2.5.4 Highly disturbed (HD) waters ..................................................................................................................... 15

2.6 Deriving local water quality guidelines and objectives for Great Barrier Reef coastal / marine waters ..... 16

Marine waters seaward of the plume line ............................................................................................................ 16

Marine waters landward of the plume line ........................................................................................................... 16

2.7 Derivation of groundwater quality guidelines .............................................................................................. 17

3 References .......................................................................................................................................................... 20

Appendix 1: Flow separation to derive low flow and high flow water quality guidelines ............................................. 21

Appendix 2: Toxicant guidelines ................................................................................................................................. 23

Deciding aquatic ecosystem indicators and local water quality guidelines under section 7 of the EPP Water

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1 Introduction

1.1 This guideline

This document informs the development of water quality guidelines to enhance or protect the ‘aquatic ecosystem’ environmental value for Queensland waters, in accordance with the provisions of the Environmental Protection (Water) Policy 2009 (EPP Water)1. Water quality guidelines form a technical basis for water quality objectives under Schedule 1 of the EPP Water. This document outlines protocols for comparing test site water quality against relevant water quality objectives recognised under the EPP Water, including for example, as input to regional report cards2. Queensland waters3 comprise tidal and non-tidal waters, including groundwaters.

Prior to determining the need for local guidelines, readers should review whether local values and objectives have been or are being established under the EPP Water for their waters. Refer to the department’s website for information: https://environment.des.qld.gov.au/water/policy/index.html.

The scope of this document is limited to providing guidelines for aquatic ecosystem physical and chemical indicators, excluding toxicants4. However, guidelines for metals may be derived where natural background levels of metals exceed ANZG 2018 default guideline values (DGVs, previously termed ‘trigger values’). The application of the ANZG 2018 toxicant DGVs in Queensland is summarised in Appendix 2.

Human use environmental values (e.g. suitability for stock watering, recreation etc.) are not part of this document.

1.2 Background

The purpose of the EPP Water is to achieve the objective of the Environmental Protection Act 1994 in relation to Queensland waters—i.e. protect Queensland’s water environment whilst allowing for development that is ecologically sustainable.

Section 5 of the EPP Water states the purpose of the EPP Water is achieved by—

identifying environmental values and management goals for Queensland waters

stating water quality guidelines and water quality objectives (WQOs) to enhance or protect the environmental values

providing a framework for making consistent, equitable and informed decisions about Queensland waters, and

monitoring and reporting on the condition of Queensland waters.

Figure 1 depicts Queensland’s water quality management framework under the EPP Water.

Section 9 of the EPP Water identifies that water quality objectives (WQOs) for Queensland waters are listed in EPP Water schedule 1, or in the absence of schedule 1, they are the set of water quality guidelines that protect all environmental values of the water. In deciding local water quality guidelines for Queensland waters, Section 7 of the EPP Water gives precedence to site specific studies for a water (i.e. local studies). As shown in Figure 1, water quality guidelines form the technical basis for deriving draft WQOs under the EPP Water.

EPP Water environmental values and water quality objectives are considered in government decision making, ecosystem health reporting and other planning contexts. For example, the Environmental Protection Regulation 2008 (section 51) outlines matters to be complied with for environmental management decisions, include the following links to the EPP Water—

the management hierarchy (EPP Water section 13), environmental values (section 6), water quality objectives (sections 10 and 11), and

1 This guideline is informed by the Queensland Water Quality Guidelines (2009, as amended) and the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZG, 2018).

2 Note that for assessing compliance of individual licence conditions, additional or different protocols and procedures may apply.

3 Under the Acts Interpretation Act 1954, Queensland waters means all waters that are — (a) within the limits of the State; or (b) coastal waters of the State 4 Under ANZG 2018, ‘toxicant’ is a substance capable of producing an adverse response (effect) in a biological system, which may seriously injure structure or function or produce death at sufficiently high concentration. Examples include pesticides, heavy metals and biotoxins.

https://environment.des.qld.gov.au/water/policy/index.html


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management intent (section 14)

1.3 Key terms

The following terms are relevant to this document. For further information, refer to definitions in the EPP Water schedule 2 and ANZG 2018.

Aquatic ecosystem means a community of organisms living within or adjacent to water, including riparian or foreshore areas.

AWQ guidelines (ANZG 2018) means the national guidelines made by the Commonwealth under the program known as the National Water Quality Management Strategy. Note the AWQ guidelines were updated in 2018 and are available from http://waterquality.gov.au/.

Default guideline value (DGV) means a guideline value recommended for generic application in the absence of a more specific guideline value (e.g. a site-specific guideline value) in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Formerly known as ‘trigger value’.

Environmental values (EVs) are particular values or uses of the environment that are important for a healthy ecosystem or for public benefit, welfare, safety or health and that require protection from the effects of pollution, waste discharges and deposits. The environmental values for waters to be enhanced or protected are stated under section 6 of the EPP Water and include aquatic ecosystem and human (e.g. agriculture, recreation, industry) values.

Guideline value means a measurable quantity (e.g. concentration) or condition of an indicator for a specific environmental value below which (or above which, in the case of stressors such as pH, dissolved oxygen and many biodiversity responses) there is considered to be a low risk of unacceptable effects occurring to that environmental value. (Also refer to default guideline value and site-specific guideline value.)

An indicator for an environmental value is a physical, chemical, biological or other property that can be measured or decided in a quantitative way (e.g. concentration of nutrients and pH)—to provide a measure of the quality of water or the condition of the aquatic ecosystem.

Indicators and water quality guidelines for environmental values are stated under section 7 of the EPP Water.

“For a particular water the indicators and water quality guidelines for an environmental value are decided using the following documents (in order of preference)—

site (i.e. local) specific documents for the water;

the Queensland Water Quality (QWQ) Guidelines;

the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZG 2018), and

other relevant water quality guidelines published by a recognised entity”—defined at EPP Water Schedule 2.

Level of aquatic ecosystem protection means the level of quality implied by the selected management goals and

water quality objectives for the water. Under the EPP Water there are four levels—see Table 1.

Management goals are long-term management objectives that can be used to assess whether the corresponding environmental value is being maintained. They reflect the management objectives with respect to EVs, e.g. the level of protection of aquatic ecosystems and key aspects of the water that must be protected. Management goals are stated under section 9 of the EPP Water.

The management hierarchy for an activity that may affect a water is stated under section 13 of the EPP Water.

The management intent for waters subject to an activity that releases waste water or contaminants to waters is stated under section 14 of the EPP Water.

Median is the middle value in a sequence of numbers (i.e. the 50th percentile).

Percentile means the division of a frequency distribution into one hundredths. For example, the 20th percentile is the value (or score) below which 20% of the observations may be found.

Reference condition means an environmental quality or condition that is defined from as many similar systems as possible and used as a benchmark for determining the environmental quality or condition to be achieved and/or maintained in a particular system of equivalent type.

Site-specific guideline value means a guideline value that is relevant to the specific location or conditions that are the focus of a given assessment or issue.

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Stressors means the physical, chemical or biological factors that can cause an adverse effect in an aquatic ecosystem as measured by the condition indicators.

Water quality guidelines (WQGs) are quantitative measures or statements for indicators, including contaminant concentration or sustainable load measures of water that protect a stated environmental value. (The term ‘water quality guideline’ under the EPP Water is equivalent to the term ‘guideline value’ under ANZG 2018—refer ‘guideline value’.)

Water quality objectives (WQOs) for waters are the set of water quality guidelines that will protect all environmental values for the water—see EPP Water sections 10 and 11. Water quality objectives (WQOs) are numerical concentrations, contaminant load measures or narrative statements that have been established to support and protect the stated environmental values for a water for a sub-catchment or management unit. Water quality objectives are based on scientific criteria or water quality guidelines but may be modified by economic and social impacts as stated under sections 10 and 11 of the EPP Water.

Figure 1 Queensland's water quality management framework under the EPP Water

Consultation Community, industry,

commerce and government—uses

and values

Draft EVs and Management Goals

(includes Level of Aquatic Ecosystem

Protection)

Water Quality Guidelines

Local WQGs

Qld/GBRMPA WQGs

National WQGs

Other WQGs

Draft WQOs

Consider social & economic impacts of

protecting EVs

EVs & WQOs approved by government—

EPP Water Schedule 1 amended

Monitoring, evaluation

and review

Consultation—community, industry, commerce and

government


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2 Deriving local water quality guidelines that protect the aquatic ecosystem environmental value

2.1 Levels of aquatic ecosystem protection

The EPP Water section 14 defines four levels of protection for the aquatic ecosystem EV, as stated in Table 1 and depicted in Figure 2. The methods for deriving water quality guidelines depend on the level of aquatic ecosystem protection decided for a water. Further information on water type mapping and level of aquatic ecosystem protection for a water is provided in the EPP (Water) 2009 Management Intent and Water Type Mapping Methodology 2018, published on the Department’s website (https://environment.des.qld.gov.au/water/policy/pdf/eppw-mapping-procedure-guide.pdf).

Table 1 Level of aquatic ecosystem protection and management intent

Level of aquatic ecosystem protection

Description (see Figure 2 below) Management Intent

High Ecological Value waters (HEV)

Waters in which the biological integrity of the water is effectively unmodified or highly valued.

Maintain natural values/condition

Slightly Disturbed waters (SD)

Waters that have the biological integrity of high ecological value waters with slightly modified physical or chemical indicators.

Maintain current condition and progressively improve towards HEV

Moderately Disturbed waters (MD)

Waters in which the biological integrity of the water is adversely affected by human activity to a measurable degree.

Maintain WQOs or improve towards WQOs (depending on current water quality)

Highly Disturbed waters (HD)

Waters that are significantly degraded by human activity.

Progressively improve over time

High Ecological Value (HEV) waters Slightly Disturbed (SD) waters

Moderately Disturbed (MD) waters Highly Disturbed (HD) waters

Figure 2 Depiction of levels of aquatic ecosystem protection

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2.2. Indicators and water quality guidelines for environmental values

Water quality guidelines are identified for a broad range of indicators that protect both the aquatic ecosystems and human use environmental values. Whereas, water quality objectives protect all environmental values nominated for a water, and are based on water quality guidelines. Water quality objectives may be modified by social and economic impacts as stated under sections 10 and 11 of the EPP Water. Under the EPP Water, indicator values listed under Schedule 1 are stated as water quality objectives.

The scope of aquatic ecosystem related indicators includes, for example:

physical and chemical indicators (e.g. pH, nutrients, suspended solids, water clarity, salinity, dissolved

oxygen). These indicators may be applied to surface or ground waters.

biological indicators (e.g. in-stream biota—fish, macroinvertebrates, aquatic macrophytes—seagrass extent

and distribution, coral extent and distribution, groundwater stygofauna)

toxicant indicators (see Appendix 1 for further details). Toxicants are stated in ANZG 2018 or derived from specific studies by a recognised entity. The guideline values for toxicants are determined by direct testing of the impacts (both lethal and sub-lethal) of the toxicant on target organisms.

physical form indicators (e.g. beds, banks, in-stream habitat, refuge waterholes and ground cover)

habitat indicators (e.g. measures of the health of the riparian zone such as width, continuity, species

composition)

hydrology indicators and environmental flows (e.g. measures of alteration to flow, changes to peak or

baseflow, changes in seasonality, changes to groundwater levels.) See also Water Act 2000 and Water

(Resource) Plans.

While the above describes the scope of indicators that are used to set water quality guidelines for Queensland waters, this document relates only to deriving guidelines for physical and chemical indicators which will protect the environmental values of aquatic ecosystems.

2.3. Spatial definition of waters, water types and management intent

Because water quality varies naturally across different water types, different water quality guidelines need to be developed for each water type. Examples of major water types include groundwaters (by main aquifer type, e.g. alluvial, fractured rock, Great Artesian Basin), surface freshwaters (upland and lowland, lakes and wetlands), estuaries (upper, mid, and lower, and estuarine wetlands), coastal waters (enclosed coastal, open coastal), and marine waters (e.g.mid-shelf and off-shore).

In some regions, water quality guidelines may need to be derived at a local catchment/sub-catchment/water quality zone level instead of, or in addition to the water type. At a local level there can be further subdivisions of water types based on geomorphology, geology, climate or other factors.

EPP Water Schedule 1 documents and mapping identify water quality objectives according to water types, level of protection/management intent, and other characteristics. (These are available from the department’s website.) The spatial definition of mapping can range from the limit of Queensland waters, to an entire basin, to a sub-catchment, or estuary, depending on the project area. Also refer to the EPP (Water) 2009 Mapping Methodology 2018 for more details.

2.4 General approaches for deriving local water quality guidelines for aquatic ecosystems

The Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZG, 2018) states that “aquatic ecosystems are complex and heterogeneous and it is often essential to reflect local condition in the guideline values.” Guideline values may be derived using either ecological effects or reference site data. The ANZG recognise that “For modified ecosystems, ‘best available’ reference sites may provide the only choice for the reference condition”5.

5 ANZG 2018 http://www.waterquality.gov.au/anz-guidelines/monitoring/data-analysis/derivation-assessment , accessed 6/12/18

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2.4.1 Using ecological effects data

This involves the measurement of the statistical distribution of water quality indicators at a specific site and the study of the ecological and biological effects of physical and chemical stressors. The locally derived water quality guideline value is defined as the level of key physical or chemical stress below which ecologically or biologically meaningful changes do not occur, i.e. the acceptable level of change. In the absence of local information on toxicant (e.g. metal, pesticides) ecological effects, reference is made to ANZG default guideline values6.

In the absence of information on the ecological and biological effects of physical and chemical stressors for Queensland waters, the reference data approach (below) is used to derive water quality guideline values for physical and chemical indicators for all Queensland waters. This approach would not be applied to man-made toxicants but may be applied where natural background levels of toxicants (e.g. metals) exceed the ANZG default guideline values that would normally be applied to that water type.

2.4.2 Using reference site data

Based on an acceptable change from reference condition, an appropriate percentile of the reference data distribution is used to derive the water quality guideline value. A percentile represents a measure that can be applied to data whether normally or non-normally distributed.

The approach is suited to physical and chemical indicators that indirectly affect the aquatic ecosystem health when at naturally observed levels, such as nutrients and turbidity. For some indicators, such as dissolved oxygen and pH, guideline values are generally derived using the reference approach but consideration also needs to be given to managing extreme values of these indicators, which can be directly toxic.

2.4.3 Approach under this guideline—in accordance with sections 10 and 11 of the EPP Water.

The approach uses reference site data for high ecological value waters and slightly disturbed waters, and the best available local site data for moderately disturbed waters to derive relevant water quality guideline values for physical and chemical indicators.

2.5 Deriving local water quality guidelines and comparison of test site data with guidelines/objectives

This section outlines the approach to derive aquatic ecosystem water quality guidelines in surface waters, and the comparison of test site data with the derived values. This framework can be used to compare water quality condition relative to the state’s adopted values, for example in catchment or regional report card processes7. Water quality guidelines form the basis for water quality objectives (WQOs) under the EPP Water. Where WQOs are scheduled, the test site data is compared against the EPP Water WQOs. Note that further detail is provided in subsequent sections for Great Barrier Reef marine waters and groundwaters.

The general principles are outlined below, followed by more detail according to level of protection/ecosystem condition (HEV, SD, MD, HD).

Identify the basin/catchment/sub-catchment/management unit waters, water types and level of aquatic ecosystem protection for your study area

Identify any reference sites or best available local sites, within each water type, where water quality data is available. If no water quality data is available, default state or national guidelines may be used whilst data is collected.

Compile sufficient water quality monitoring data to allow reliable percentiles to be determined. Refer ‘data’ section below. The precision with which the percentile is estimated depends on sample size—see ANZG 2018.

Water quality monitoring and sampling must be undertaken in accordance with the EPP Water Monitoring and Sampling Manual 2018, published on the Department’s web site.

6 ANZG 2018 http://www.waterquality.gov.au/anz-guidelines/guideline-values/default , accessed 10/12/18

7 Note that for assessing compliance of individual licence conditions, additional or different protocols and procedures may apply.

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set the water quality guidelines based on one or more of the percentiles8 of the indicator results, as outlined in the following section. Extensive data screening must be undertaken to limit anthropogenic impacts for best available local sites—see 2.5.3.

2.5.1 High ecological value (HEV) waters

Reference sites: HEV waters are by definition un-impacted: see Table 1. If water quality monitoring data are limited, reference data from HEV waters in the same or comparable catchment and water type may be considered.

Data: Queensland water quality guidelines recommend a minimum of 18 data values collected over two years to

derive guidelines. (See QWQ Guidelines section 4.4.3.1 regarding sample data quantity and Figure 4.4.1 on the relationship between sample size and the error in estimation of percentile values.) Larger data sets give increasing reliability and ideally a data set should encompass several years and a range of climate conditions. While the QWQ Guidelines permits the derivation of guidelines based on less than two years of monthly sampling, this should be considered as interim—until a full data monitoring program can be undertaken.

Sampling errors can potentially contribute significantly to the overall errors in percentile estimates. Therefore, all reference and compliance data monitoring programs must have quality assurance programs and data collection, in accordance with the EPP Water Monitoring and Sampling Manual 2018, published on the Department’s website.

Flow separation and seasonality: Flow separation of reference data (i.e. into low flow and high flow) should be carried out wherever flow data exists for that sub-catchment from the relevant gauging station—refer to the DNRME website for gauging station locations. Flow separated data may then be used to derive flow specific water quality guidelines. These guidelines then apply under the same flow conditions for which flows were defined. See Appendix 1 for details on defining low and high flow conditions. Further, the data need to be checked for seasonal differences, e.g. when deriving coastal waters turbidity guidelines from continuous turbidity monitoring data.

HEV guidelines:

Low flow:

Guideline: 20/50/80th percentiles of the low flow data.

High Flow:

Guideline: 20/50/80th percentiles of the high flow data.

Comparison of test site data with EPP Water WQOs (or water quality guideline)

Under the EPP Water, the management intent for HEV waters is that there should be ‘no change’ to existing water quality, i.e. no change in the natural range of values. No change is deemed to have occurred if there are no detectable changes to the 20th, 50th and 80th percentiles of the natural distribution of values. For DO and pH, test sample median values are compared with, and should fall within, the specified percentile range.

The testing regime is stated in the QWQ Guidelines, Appendix D.2.1.

8 The approach under Section 2.5 is consistent with ANZECC 2000, section 2.2.1.4 “Tailoring guidelines for local conditions”

“Optimum water quality characteristics differ between regions. There is a wide range of ecosystem types and environments in Australia and New Zealand, and it is not possible to develop a universal set of specific guidelines that apply equally to all. Further, environmental factors can significantly alter the toxicity of physical and chemical stressors at a site and these factors can vary considerably among sites. The present Guidelines move away from single number values that are mostly conservative, and emphasise guidelines that can be determined individually, according to local environmental conditions. This is done through the use of local reference data...”


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2.5.2 Slightly disturbed (SD) waters

Reference sites: Reference data are sourced from SD waters.

Note: Under the EPP Water, the inclusion of the SD level of protection was specifically targeted to include those waters that were assessed to be minimally impacted with management intent to achieve natural/unmodified condition.

In accordance with the EPP Water management intent, the water quality guidelines are set on a more stringent percentile than the existing water quality—to improve towards HEV. If water quality monitoring data are limited for the SD waters in question, reference data from HEV or SD waters in the same or comparable catchment and water type may be considered.

Data: QWQ Guidelines recommends a minimum of 18 data values collected over 2 years to derive guidelines. (See QWQ Guidelines section 4.4.3.1 regarding sample data quantity and Figure 4.4.1 on the relationship between sample size and the error in estimation of percentile values.) Larger data sets give increasing reliability and ideally a data set should encompass several years and a range of climate conditions. While the QWQ Guidelines permit the derivation of guidelines based on less than two years of monthly sampling, this should be considered as interim—until a full data monitoring program can be undertaken.

Sampling errors can potentially contribute significantly to the overall errors in percentile estimates. Therefore, all reference and compliance data monitoring programs must have quality assurance programs and data collection in accordance with the EPP Water Monitoring and Sampling Manual 2018, published on the Department’s website.

Flow separation and seasonality: Flow separation of reference data (i.e. into low flow and high flow) should be carried out wherever flow data exists for that sub-catchment from the relevant gauging station—refer to the DNRME website for gauging station locations. Flow separated data may then be used to derived flow specific water quality guidelines. These guidelines then apply under the same flow conditions for which flows were defined. See Appendix 1 for details on defining low and high flow conditions. Further, the data need to be checked for seasonal differences, e.g. when deriving coastal waters turbidity guidelines from continuous turbidity monitoring data.

SD Guidelines: Low flow:

Guideline: 20/40/70th percentiles of the existing SD water quality (30/60/80th percentiles for

indicators with impact at low level or concentration). If limited data, review percentiles from

comparable HEV catchment and water type (20/50/80th percentiles), or comparable SD catchment

and water type (20/40/70th percentiles).

High flow:

Guideline: 20/40/70th percentiles of the existing SD water quality (30/60/80th percentiles for

indicators with impact at low level or concentration). If limited data, review percentiles from

comparable HEV catchment and water type (20/50/80th percentiles), or comparable SD catchment

and water type (20/40/70th percentiles).


Under the EPP Water, the management intent for SD waters is to maintain current condition and progressively improve towards HEV.

The test site 20th, 50th and 80th percentiles are compared with the corresponding water quality objective distribution stated in EPP Water Schedule 1 for the SD waters. This protocol is designed to promote improvement in water quality compared to existing condition as required by the EPP Water. For DO and pH, test sample values are compared with, and should fall within the specified percentile range.


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2.5.3 Moderately disturbed (MD) waters

Under the previous ANZECC Guidelines (ANZECC 2000) approach, guidelines for MD waters have commonly been based on data from largely undisturbed reference sites. Issues associated with this approach are:

largely unimpacted reference sites are often not available for many areas, particularly lowland freshwaters

guidelines based on data from unimpacted reference sites may be unattainable in MD waters in the foreseeable future and thus may be seen as having little practical application

the derivation of 80th percentile guideline values based on modified ‘reference’ sites has potential to set water quality benchmarks of poorer quality than intended.

These issues can be largely addressed through use of a broader application of the reference site concept. Thus, while reference sites are commonly taken to be undisturbed sites, ANZG 2018 allows for the reference concept to include sites that are used to derive the quantitative values for particular physical or chemical indicators.9 “For modified ecosystems ‘best available’ reference sites may provide the only choice for the reference condition”. Use of best available reference sites allows for reference data to be acquired in areas where there are no unimpacted reference sites. It can also, with appropriate provisions, be used to determine water quality guidelines that are potentially attainable in the foreseeable future in disturbed waters.

Where (a) no largely unimpacted reference sites are available or (b) use of unimpacted reference sites results in unrealistic management goals, the use of best available local sites is adopted when deriving water quality guidelines for moderately disturbed waters.

Where guidelines for MD waters are based on data from undisturbed reference sites, the 80th percentile of the reference data is by default used to derive a water quality guideline. Where reference data from best available local sites is employed, the approach to setting a water quality guideline is to use a more stringent percentile, generally less than the median, aiming to both protect the aquatic ecosystem EV and guide improvements in water quality. The EPP Water requires MD water quality objectives be set to improve water quality.

The use of the 40th percentile is a starting point for stakeholder consultation and consideration by the Department, in accordance with sections 10 and 11 of the EPP Water. The consultation process may identify management goals that require more stringent protection, i.e. the water quality objective is set lower than the 40th percentile. In the few situations where reliable modelling of the water quality attainable through best management practice is available, it may be optional to set guidelines based on these values, in accordance with sections 10 and 11 of the EPP Water.

The policy framework aims for continual improvement in water quality to protect EVs. Therefore, after the first application of this guideline development method using locally derived data, future reviews of the guidelines should only seek to maintain or improve on the initially developed guideline values. This will prevent future guidelines being revised down due to declining trends in water quality.

The Department will recommend the final water quality objectives to be included in the EPP Water in consultation with local government, industry and the community; and in consideration of the economic and social impact of protecting the environmental values for the water.

Notes: 1. For DO and pH, guideline values (typically a range between 20th and 80th percentiles) are set with

reference to the QWQ Guidelines and review of local data.

2. Post implementation of management actions to improve water quality, should water quality monitoring and evaluation data determine the legislated WQOs are achieved for MD waters—in conjunction with stakeholders, the Department will recommend re-establishing the WQOs in accordance with EPP Water sections 10 and 11.

3. Additionally, there will be a need to confirm that regardless of which approach is employed, calculated values are not inconsistent with data from sites in comparable areas and do not represent a direct threat to the biota. It is also a requirement of the EPP Water that guideline values represent an improvement from current water quality.

9 The approach is consistent with ANZECC 2000 Volume 1, section 3.3.2.4, that notes the defining of water quality guidelines in terms of percentiles obtained from an appropriate reference condition “is arbitrary though reasonably conservative”.


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4. The approach under this guideline is similar to that adopted by the NSW Government in deriving guideline (trigger) values for lowland rivers10. The Victorian approach is also to set water quality objectives for modified ecosystem conditions—between current and desired condition—to facilitate greater management action in addressing problems. See ANZG 2018.

2.5.3.1 Use of best available local sites for moderately disturbed (MD) waters

Best available local sites: An assessment of the complete water quality data sets within each basin/catchment /sub-catchment and water type is undertaken to identify the best available (least disturbed) local sites.

The location of best available local sites should not be impacted by, or immediately downstream of—

a point source discharge, or

identified diffuse emissions, or

identified urban diffuse emissions, or

severe bank or gully erosion.

Queensland Government and stakeholder databases, land-use data, satellite imagery or field checks should be used to identify best available local sites before proceeding to derive water quality guideline values.

Strict data screening of ‘raw’ data must be adopted. Water quality at all available sites should be reviewed. Any sites with clearly anomalous or degraded water quality (e.g. from historical or current activities) should be removed from the analysis. Temporal trends in the data should also be considered. For instance, if water treatment infrastructure or other upgrades have resulted in improved water quality, only the more recent better quality data are used. Where recent actions have resulted in degradation of water quality, then recent data should not be included in the dataset used to derive water quality objectives. Where sites are clearly different from others, the sites should be assessed to determine if this is due to natural differences (e.g. geology) between catchments. If this is the case, it may be necessary to subdivide the area and calculate separate guidelines for each.

If remaining sites have reasonably consistent water quality, then guideline percentiles can be determined.

Data: Because data is taken from the best available local sites, the data should be sourced from a range of sites so that there can be confidence that water quality in the catchment is adequately characterised. QWQ Guidelines recommends a minimum of 18 data values collected over 2 years to derive guidelines (See QWQ Guidelines section 4.4.3.1 regarding sample data quantity and Figure 4.4.1 on the relationship between sample size and the error in estimation of percentile values.) Larger data sets give increasing reliability and ideally a data set should encompass several years and a range of climate conditions. While the QWQ Guidelines permits the derivation of guidelines based on less than two years of monthly sampling, this should be considered as interim—until a full data monitoring program can be undertaken.



MD Guidelines:

Low flow:

Guideline: Based on the 40th percentile of best available local reference data

High flow:

Guideline: Based on the 40th percentile of best available local reference data.

10 ANZECC 2000 Volume 2. Table 8.2.2.2 extract, NSW: Only sites judged fair to good condition were used. It is recommended that the 50th percentiles be used in the final table as there are no undisturbed lowland rivers and hence an 80th percentile includes values for significantly disturbed systems. This is inappropriate for trigger values.”


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The use of the 40th percentile is a starting point for stakeholder consultation and consideration by the Department, in accordance with sections 10 and 11 of the EPP Water.


The median value of preferably five or more independent samples at test sites should not exceed the water quality objective established under the EPP Water and stated in Schedule 1 for the water. (If a range of WQOs [e.g. 20th-50th-80th percentile] has been included in the EPP water schedule materials for MD waters, then the median of the test data is compared with the corresponding median WQO.) For DO and pH, test sample median values are compared with, and should fall within the specified percentile range.

This protocol is designed to promote improvement in water quality compared to existing condition towards achievement of the water quality objective—in accordance with the management intent and as required by the EPP Water.

2.5.3.2 Use of unimpacted reference sites for moderately disturbed (MD) waters

Reference sites: The method is applied to MD waters for which data from unimpacted reference sites are available for the same water type. (Criteria for unimpacted reference sited for MD waters are listed in Table 2).

Note that in developed regions (i.e. most of Queensland), unimpacted sites are very rare.

Table 2 Criteria for un-impacted reference sites

From QWQ Guidelines Table 4.4.1

1 No intensive agriculture within 20km upstream. Intensive agriculture is that which involves irrigation, widespread soil disturbance, use of agrochemicals and pine plantations. Dry land grazing does not fall in this category.

2 No major extractive industry (current or historical) within 20km upstream. This includes mines, quarries and sand/gravel extraction.

3 No major urban area (>5000 population) within 20km upstream. If the urban area is small and the river large this criterion can be relaxed.

4 No significant point source wastewater discharge within 20km upstream. Exceptions can again be made for small discharges into large rivers.

5 Seasonal flow regime not greatly altered. This may be by abstraction or regulation further upstream than 20km. Includes either an increase or decrease in seasonal flow.

Estuaries

1 No significant point source wastewater discharge within the estuary or within 20km upstream. Exceptions can again be made for small discharges into large rivers.

2 No major urban area (>5000 population) within 20km upstream. If the urban area is small and the river large this criterion can be relaxed.

Data: QWQ Guidelines recommends a minimum of 18 data values collected over two years to derive guidelines. (See QWQ Guidelines section 4.4.3.1 regarding sample data quantity and Figure 4.4.1 on the relationship between sample size and the error in estimation of percentile values.) Larger data sets give increasing reliability and ideally a data set should encompass several years and a range of climate conditions. While the QWQ Guidelines permits the derivation of guidelines based on less than two years of monthly sampling, this should be considered as interim—until a full data monitoring program can be undertaken.



MD Guidelines: Low flow:

Guideline: The 80th (or 20th for indicators with impacts at low level or concentration) percentile of low flow un-impacted reference site data.

High Flow:

Guideline: The 80th (or 20th for indicators with impacts at low level or concentration) percentile of high flow un-impacted reference site data.


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The median value of preferably five or more independent samples at test sites should not exceed the water quality objective established under the EPP Water and stated in Schedule 1 for the water. For DO and pH, test sample median values are compared with, and should fall within the specified percentile range.


2.5.4 Highly disturbed (HD) waters

HD waters are significantly degraded by human activity. Some HD waters are subject to significant levels of historical pollution and have highly degraded ecosystems, while others may have water quality that exceeds guidelines for some indicators, but still support a functioning ecosystem. For HD waters the management intent under the EPP Water is to progressively improve water quality. In extreme cases the initial management goal towards achieving the management intent may be to halt further degradation. Other waters may have management goals of restoring certain ecological process or to support a certain biotic community. However, wherever possible, the management goal would be to return the water to an MD level of protection.

Post implementation of management actions to improve water quality, should water quality monitoring and evaluation data determine the legislated water quality objectives (WQO) are achieved for HD waters—in conjunction with stakeholders, the Department will re-establish the WQOs in accordance with EPP Water sections 10 and 11.

The guideline derivation method is in accordance with the management intent.

Data: QWQ Guidelines recommends a minimum of 18 data values collected over 2 years to derive guidelines. (See QWQ Guidelines section 4.4.3.1 regarding sample data quantity and Figure 4.4.1 on the relationship between sample size and the error in estimation of percentile values.) Larger data sets give increasing reliability and ideally a data set should encompass several years and a range of climate conditions. While the QWQ Guidelines permits the derivation of guidelines based on less than two years of monthly sampling, this should be considered as interim—until a full data monitoring program can be undertaken.



HD Guidelines: Low flow:

Guideline: The 20th percentile of low flow best available local data High flow:

Guideline: The 20th percentile of high flow best available local data


The median value of preferably five or more independent samples at test sites should not exceed the water quality objective established under the EPP Water and stated in Schedule 1 for the water. For DO and pH, test sample median values are compared with, and should fall within, the specified percentile range.



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2.6 Deriving local water quality guidelines and objectives for Great Barrier Reef coastal / marine waters

The derivation is applicable to all open coastal waters, mid-shelf waters and off-shore waters north of 24 .29’.54”S to 10 .10’. 66”S and within the east and west boundaries of the Great Barrier Reef Marine Park and Great Barrier Reef World Heritage Area.

The following has been adopted by Great Barrier Reef Marine Park Authority (GBRMPA) in localising water quality guidelines for different coastal/marine waters throughout the Great Barrier Reef. The guidelines form a basis for scheduling as water quality objectives under the EPP Water. Further details on datasets used in particular regions is contained in region reports published on the Department’s website.

In deriving local guidelines for open coastal, mid-shelf and offshore marine waters, GBRMPA reviewed Australian Institute of Marine Science (AIMS) data (including continuous logger data) from the Marine Monitoring Program (MMP) and Long Term Monitoring Program (LTMP). All data are collected and analysed (including for seasonal trends) in accordance with an approved Quality Assurance and Quality Control manual available at the GBRMPA website.

In accordance with the principles in Section 2.4 above, the approach has been to use locally applicable water quality data from the AIMS monitoring programs and compare this for particular waters and water types against the corresponding GBRMPA water quality guidelines (GBRMPA, 2010), for the same water type.

Marine waters seaward of the plume line

Waters seaward of the plume line are generally expected to be in natural or near natural (i.e. high ecological value) condition in terms of their water quality.

Where review of water quality data indicates local water quality condition was better than the GBRMPA (2010) ecosystem support guidelines for the given water type, and there was sufficient data to do so, percentiles were set to maintain this better water quality condition (e.g. by specifying 20-50-80th percentiles, including any seasonal split where applicable). These are then recommended as the basis for updated water quality objectives under the EPP Water.

If percentiles based on local water quality data were worse than the GBRMPA (2010) ecosystem support guidelines, then the GBRMPA guidelines are adopted as the basis for updated water quality objectives.

For indicators not covered by the GBRMPA guidelines, reference should be made to the applicable QWQG or ANZG 2018.

Marine waters landward of the plume line

The approach for GBR waters landward of the plume line follows a similar approach to the above.

Where review of water quality data indicates local water quality condition is better than the GBRMPA (2010) guidelines for the given water type, and there was sufficient data to do so, percentiles are set to maintain this better water quality condition (e.g. by specifying 20-50-80th percentiles, including any seasonal split where applicable). These are then recommended as the basis for updated water quality objectives.

If percentiles based on local water quality data are worse than the GBRMPA (2010) ecosystem support guidelines, then the GBRMPA (2010) guidelines are adopted as the basis for updated water quality objectives. Waters landward of the plume line are at greatest risk from poor water quality, and are generally found to not meet GBRMPA (2010) guidelines.

Hence, for these waters the intent is to improve water quality over time to achieve GBRMPA (2010) water quality guideline values.

For indicators not covered by the GBRMPA guidelines, reference is made to the applicable QWQG or ANZG 2018.

Plume line derivation

The plume discharge area from waters discharging to Great Barrier Reef waters is mapped from the southern to the northern limit of GBR waters, bounded by the plume line that is derived from a smoothed version of the ‘high’ and ‘very high’ risk classes of modelled outputs from the risk assessment element of the Reef Plan Scientific Consensus Statement 2013 (Waterhouse et al. 2013). See EPP Water mapping methodology 2018.


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The same process as per previous sections is recommended. However, some parameters in marine waters have single values specified as an annual (or seasonal) mean, rather than median. The mean water quality value of a number of independent samples at a particular monitoring ('test') site should be compared against the applicable water quality objective. The sample number is preferably five or more samples for within season comparison, and five or more [preferably 24 or more over two years] samples taken during wet and dry seasons for annual mean comparisons. While seasonal means are estimated based on biotic responses, the relationship is not as strong as it is for annual mean values. They are provided in relevant EPP Water schedule documents as indicative objectives to allow comparison with single season collected data sets. Wet and dry seasons can start and end at different times of the year. Seasonal dates indicated are generally applicable. Applying these values for any management action should take both of these matters into account.

2.7 Derivation of groundwater quality guidelines

This section provides guidance on the approach taken to identifying environmental values, water quality indicators and guidelines (as a basis for WQOs) in groundwaters.

Policy context

Where local EVs and WQOs have been scheduled under the EPP Water for groundwaters, these are the applicable reference source for decision making. In the absence of scheduled information, the EPP Water identifies applicable EVs (section 6) and potential sources for water quality guidelines (section 7) to inform decision making. The Environment Protection Act 1994 identifies that groundwater quality is an environmental value to be protected. Therefore, the intrinsic environmental value of groundwater should be protected and the groundwater quality should be maintained within the range of natural quality variations, established through baseline characterisation to ensure that no adverse effect on groundwater quality occur. In the absence of scheduled data the default management intent is that there should be ‘no change’ to the natural variation in groundwater quality. From the QWG Guidelines, no change in the natural variation in groundwater quality is deemed to have occurred if there are no detectable changes to the 20th, 50th and 80th percentiles of the natural distribution of values.

Where review of local data indicates that some groundwater systems are clearly impacted e.g. through application of nitrogen fertilisers, then in these cases, the management intent would be to improve quality, and more stringent percentiles may be used to derive guideline values.

Further policy guidance is provided in materials supporting the National (ANZG, 2018) water quality guidelines. In particular, refer to the National Water Quality Management Strategy (NWQMS) policy paper Guidelines for groundwater quality protection in Australia, prepared, available from http://www.waterquality.gov.au/guidelines/groundwater.

Protection of groundwater quality is imperative to ensure the protection of healthy ecosystems and maintenance of environmental values as well as for future economic and population growth.’ (Australian Government, 2013;1)

‘These guidelines support a national approach to groundwater quality protection that applies to all groundwater in Australia, regardless of the current or potential uses of the groundwater. The national application of the guidelines will enable management of groundwater quality of aquifers, as well as their connected surface water systems, across traditional management boundaries. Groundwater quality protection also applies to groundwater that extends under coastal waters. (Australian Government, 2013;5)

This complements the policy established for groundwaters in the ANZECC 2000 guidelines:

Groundwater is an essential water resource for many aquatic ecosystems, and for substantial periods it can be the sole source of water to some rivers, streams and wetlands. Groundwater is also very important for primary and secondary industry as well as for domestic drinking water, particularly in low rainfall areas with significant underground aquifers. Generally these Guidelines should apply to the quality both of surface water and of groundwater since the environmental values which they protect relate to above-ground uses (e.g. irrigation, drinking water, farm animal or fish production and maintenance of aquatic ecosystems). Hence groundwater should be managed in such a way that when it comes to the surface, whether from natural seepages or from bores, it will not cause the established water quality objectives for these waters to be exceeded, nor compromise their designated environmental values. An important exception is for the protection of underground aquatic ecosystems and their novel fauna. Little is known of the lifecycles and environmental requirements of these quite recently-discovered communities, and given their high conservation value, the groundwater upon which they depend should be given the highest level of protection.

‘As a cautionary note the reader should be aware that different conditions and processes operate in

http://www.waterquality.gov.au/guidelines/groundwater


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groundwater compared with surface waters and these can affect the fate and transport of many organic chemicals. This may have implications for the application of guidelines and management of groundwater quality.’ (ANZECC & ARMCANZ 2000, The Guidelines, Box 1.2; p1-2)

Identification of environmental values: At aquifer level, the bore installation records available in the DNRME water licences database11 provide the basis for deriving some human-use EVs. The bore installation records give the commencement and expiry date of the licence, stipulate the source of the water (aquifer name in the case of groundwater), list the equipment used in the bore, and detail how the water from each bore is to be used, (i.e. stock, domestic, irrigation, urban). It thus informs the derivation of EVs.

The ecosystem protection EV is always identified as a State Interest.

Indicators: The main indicators for which data are available are salinity, recorded as both Electrical Conductivity (EC) and Total Dissolved Solids (TDS), as well as the major ions, as these were historically of most interest for agricultural and domestic use. Toxicant indicators are in principle the same as those for surface waters and where data are available, values would be compared to surface water guidelines, i.e. ANZG 2018. Typical indicators include: Sodium, Calcium, Magnesium, Bicarbonate, Chloride, Sulfate, Nitrate, Electrical conductivity, Hardness, Alkalinity, Silica, Fluoride, Iron, Manganese, Zinc, Copper, Sodium adsorption ratio, Total nitrogen (TN), and Total phosphorus (TP).

Nitrate is a good indicator of Total nitrogen as virtually all groundwater nitrogen is in this form because chemical reactions in the unsaturated zone remove other forms of nitrogen while nitrate is mobile enough to be transported to the groundwater (Freeze and Cherry 1979; Canter 1997; Bouwman et al. 2005). There are very few TP measurements in the DNRME Queensland Groundwater Database (GWDB) as TP is rarely measured due to concentrations being usually low in Queensland groundwaters. This is because most of the phosphorus binds to particles in the soil and unsaturated zone, restricting its movement to the aquifer (Holman et al. 2008).

There is limited information on dissolved oxygen (DO) in groundwater (or any other gases), as it tends to be disturbed in the process of sampling and therefore difficult to measure except by probe. DO is generally low in groundwater because the oxygen gets used up in chemical reactions.

Indicators for groundwater biota (stygofauna) are not currently available. Hose et al. (2015) note that:

‘Stygofauna are generally adapted to stable environmental conditions, including water quality. Changes to water quality that are beyond the range of conditions normally experienced by stygofauna pose a threat to their survival.’ (2015;40)’.

Hence identification of current water quality characteristics is a starting point for stygofauna habitat maintenance.

Aquifer mapping definition of groundwater segments: EPP Water groundwater water type mapping is compiled using the most current groundwater datasets. These include the Australian Government geospatial data portal at https://data.gov.au/, DNRM Groundwater Alluvial Boundaries QLD (published 9/12/02), Detailed Surface Geology QLD (published 24/5/18), and additionally some individual geological and aquifer layers which were mapped for the Great Artesian Basin Water Resource Assessment (Ransley and Smerdon 2012) obtained from www.ga.gov.au. Queensland bore attribution data, and chemistry zone delineation within each of the aquifer classes vary according to region.

To enable mapping of overlying systems, the aquifers in a relevant region (e.g. the Burdekin and Fitzroy regions) were broadly grouped into a system of aquifer classes, based on the divisions used by Smerdon et al. (2012), (e.g. alluvial, fractured rock, Great Artesian Basin [GAB], pre GAB). All bores used in the study were attributed to a specific aquifer, and therefore class, and groundwater water quality data are used to spatially define chemistry zones of broadly comparable water quality within each aquifer class, included in EPP Water mapping. Current baseline water quality was then calculated for each zone, represented by percentiles of parameters recorded in the GWDB.

Reference data: The DNRME Queensland Groundwater Database contains water quality data from groundwater bore monitoring. Groundwater quality varies considerably between basins and aquifers and to a lesser but still significant extent within aquifers. Where sufficient data exist, water quality guidelines are developed at aquifer/sub-aquifer level based on existing condition, using groundwater quality data sourced from the DNRME Queensland Groundwater Database, data sourced through the Office of Groundwater Impact Assessment (OGIA) or from local monitoring data by a recognised entity.

Following the definition and mapping of chemistry zones (refer Aquifer mapping above), the groundwater quality data are used to calculate a range of percentiles for available indicators for each chemistry zone.

(Where there is potential for groundwater to be impacted by activities such as mining, it is important to acquire

11 Information on water licences is at https://data.qld.gov.au/dataset/water-entitlements.

https://data.gov.au/

http://www.ga.gov.au/

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localised reference data prior to commencement of the activity. This is necessary because of the high level of spatial variation characteristic of groundwaters. In this situation, the local pre-development data would be used as reference data.). Where the groundwater water quality is slightly disturbed due to anthropogenic contamination or from naturally occurring groundwater chemistry, the SD waters guideline applies. Where groundwater is moderately or highly disturbed, more stringent percentiles may be applied.

Guidelines:

HEV groundwaters guideline: 20/50/80th percentiles of the waters in the sub-aquifer chemistry zones.

SD groundwaters guideline: 20/40/70th percentiles of the waters in the sub-aquifer chemistry zones.

Waters potentially impacted by human activities – guideline: no change to the 20/50/80th percentiles of local pre-development data. If review of local data indicates groundwater systems are clearly impacted, then in these cases, the management intent would be to improve quality, and consideration of more stringent percentiles of current data may be required in deriving guideline values.


Under the EPP Water, the management intent for groundwaters is that there should be ‘no change’ to existing water quality, i.e. no change in the natural range of values. No change is deemed to have occurred if there are no detectable changes to the 20th, 50th and 80th percentiles of the natural distribution of values.

The testing regime is stated in the QWQ Guidelines, Appendix D.2.1.

For SD groundwaters, the test site 20th, 50th and 80th percentiles are compared with the corresponding groundwater quality objective distribution of 20/40/70th percentiles.

For more disturbed waters, the median value of preferably five or more independent samples at test sites should not exceed the water quality objective established under the EPP Water and stated in Schedule 1 for the water. For DO and pH, test sample median values are compared with, and should fall within, the specified percentile range (although for reasons outlined above there is limited information about DO in groundwaters).



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3 References ANZG 2018. Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Australian and New Zealand Governments and Australian state and territory governments, Canberra, ACT, Australia. Available from http://waterquality.gov.au/anz-guidelines/

Australian and New Zealand Environment and Conservation Council, Agriculture and Resource Management Council of Australia and New Zealand (2000) Australian and New Zealand guidelines for fresh and marine water quality. Volume 1, The guidelines. Available from http://www.waterquality.gov.au/anz-guidelines/Documents/ANZECC-ARMCANZ-2000-guidelines-vol1.pdf , accessed 10/12/18.

Australian Government 2013, Guidelines for groundwater quality protection in Australia: National Water Quality Management Strategy, Department of Agriculture and Water Resources, Canberra, March. CC BY 3.0. Available from Water Quality Australia web site, http://www.waterquality.gov.au/ , accessed 10/12/2018.

Bouwman AF, van Drecht G. and van der Hoek KW. 2005. Global and regional surface nitrogen balances in intensive agricultural production systems for the period 1970–2030. Pedosphere 15: 137-155.

Canter LW 1997, Nitrates in groundwater. CRC Press, Florida, United States of America, 59p.

Freeze, R. A., and Cherry J. A.. 1979. Groundwater. Prentice-Hall.

Department of Environment and Heritage Protection (2009) Queensland Water Quality Guidelines, Version 3, ISBN 978-0-9806986-0-2. Re-published July 2013 Environmental Protection (Water) Policy (Queensland)

DES. (2018). Monitoring and Sampling Manual: Environmental Protection (Water) Policy. Brisbane: Department of Environment and Science Government. At https://environment.des.qld.gov.au/water/monitoring/sampling-manual/

DES (2018) Environmental Protection Policy (Water) 2009 Mapping procedural guide, Management intent and water type mapping methodology. At https://environment.des.qld.gov.au/water/policy/

Environmental Protection (Water) Policy (Queensland)

Great Barrier Reef Marine Park Authority (2010). Water quality guidelines for the Great Barrier Reef Marine Park. Available from www.gbrmpa.gov.au

Holman, IP, Whelan, MJ, Howden, NJK, Bellamy, PH, Willby, NJ, Rivas-Casado, M & McConvey, P. 2008, 'Phosphorus in groundwater – an overlooked contributor to eutrophication?'. Hydrological Processes, vol. 22, no: 5121–5127.

Hose GC, J Sreekanth, Barron O, Pollino C, 2015 Stygofauna in Australian Groundwater Systems: Extent of knowledge. CSIRO, Australia.

Ransley TR and Smerdon BD (eds) (2012) Hydrostratigraphy, hydrogeology and system conceptualisation of the Great Artesian Basin. A technical report to the Australian Government from the CSIRO Great Artesian Basin Water Resource Assessment. CSIRO Water for a Healthy Country Flagship, Australia. This dataset and associated metadata can be obtained from www.ga.gov.au

Smerdon, BD, Ransley, TR, Radke, BM & Kellett, JR 2012, 'Water resource assessment for the great artesian basin. A report to the Australian Government from the CSIRO Great Artesian Basin Water Resource Assessment'. CSIRO Water for a Healthy Country Flagship, Australia., 46 pp.

Waterhouse, J., Maynard, J., Brodie, J., Randall, L., Zeh, D., Devlin, M., Lewis, S., Furnas, M., Schaffelke, B., Fabricius, K., Collier, C., Brando, V., McKenzie, L., Warne, M.St.J., Smith, R., Negri, A., Henry, N., Petus, C., da Silva, E., Waters, D., Yorkston, H., Tracey, D., 2013. Section 2: Assessment of the risk of pollutants to ecosystems of the Great Barrier Reef including differential risk between sediments, nutrients and pesticides, and among NRM regions. In: Brodie et al. Assessment of the relative risk of water quality to ecosystems of the Great Barrier Reef. A report to the Department of the Environment and Heritage Protection, Queensland Government, Brisbane. TropWATER Report 13/28, Townsville, Australia.

http://waterquality.gov.au/anz-guidelines/

http://www.waterquality.gov.au/anz-guidelines/Documents/ANZECC-ARMCANZ-2000-guidelines-vol1.pdf

http://www.waterquality.gov.au/anz-guidelines/Documents/ANZECC-ARMCANZ-2000-guidelines-vol1.pdf

http://www.waterquality.gov.au/

https://environment.des.qld.gov.au/water/monitoring/sampling-manual/

https://environment.des.qld.gov.au/water/policy/

http://www.gbrmpa.gov.au/

http://www.ga.gov.au/


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Appendix 1: Flow separation to derive low flow and high flow water quality guidelines Water quality in freshwater catchments can vary significantly dependant on flow, and water quality guidelines should be matched to flow conditions. The derivation of low and high flow guidelines and water quality objectives is required wherever flow data exists.

Flow separation is limited to sorting the data into low flow and high flow data sets. Under high flow conditions water quality is usually very different from low flow conditions—for example; salinity, sediments and nutrients.

A typical flow/quality relationship is shown in Figure 3, flow vs total suspended solids (TSS). Values are shown on log scales as this displays the spread of values more clearly. While there is obvious variability, there are also clear differences in the spread of values between low and high flows. In this example, the low /high flow divide might be placed at around 1.0 cumecs.

Figure 3 Flow vs Total suspended Solids at Taroom on the Dawson River (Fitzroy Basin), QLD.

HOWEVER DATA RELATING FLOW AND WATER QUALITY FOR SPECIFIC INDICATORS ARE GENERALLY NOT AVAILABLE AND THE FOLLOWING METHODS SHOULD BE APPLIED IN DERIVING LOW FLOW AND HIGH FLOWS:

The approach used widely in recent water quality objective reports is based on percentiles of flow (flow exceedance probabilities). The following are defaults based on flow percentiles applied to certain climate and catchment types—

in large inland, drier catchments such as the Fitzroy and Burdekin, the default to assign high flows is the upper 10th percentile of daily mean flows;

in coastal and wetter catchments such as southeast Queensland and the Wet Tropics, the default to assign high flow is the upper 20th percentile of daily mean flows; and

in small and more arid catchments, the default to assign high flow is the upper 5th percentile of daily mean flows.

Figure 4 below shows the method for assigning default high flow discharge values. The default of the upper 10th percentile of daily mean discharge is shown (left of the red line), equal to flows greater than 17 cumecs. Samples collected during these flows would be high flow data. (5th and 20th percentile flow values would be determined similarly).


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Figure 4 Flow vs Exceedance Probability at Urannah on the Broken River (Burdekin Basin), QLD.


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Appendix 2: Toxicant guidelines Toxicant indicators and default guideline values (DGVs) are stated in ANZG 2018 or derived from specific studies by a recognised entity. The guideline values for toxicants are determined by direct testing of the impacts (both lethal and sub-lethal) of the toxicant on target organisms. Guidelines for metals may be derived where natural background levels of metals exceed ANZG 2018 DGVs.

The DGVs for different levels of species protection are applied according to the current or desired ecosystem condition and associated level of protection. The levels of species protection for which DGVs are typically derived are 99% (HEV and SD waters), 95% (MD waters), 95%, 90% or 80% (HD waters). The ANZ 2018 guidelines identify certain toxicants with bio accumulative or secondary poisoning effects, and recommend a 99% species protection value for these toxicants.

In Queensland, ANZG 2018 toxicant guidelines are applied as follows:

Ecosystem protection level Toxicant Guideline – ANZG 2018 level of species protection applied 1

High Ecological Value waters 99% level of species protection

Slightly Disturbed waters 99% level of species protection

Moderately Disturbed waters 95% level of species protection

Highly Disturbed waters On a case by case basis but a default of 80%, 90% or 95% level of species protection

1. Subject to ANZG 2018 advice on bioaccumulation/other effects identified

Comparison of test site data with EPP Water WQOs (or water quality guideline) For assessing monitoring data against toxicant guidelines/objectives (in waters and sediments), the QWQG refers to the AWQG protocols (e.g. AWQG vol. 1 sections 3.5.5, 7.4.4.2 and 7.4.4.4). For toxicants in water, the AWQG recommends the comparison of the 95th percentile of monitoring data against the default toxicant trigger values.