Burnett Mary WQIP Ecologically Relevant Targets

Ecologically relevant targets for pollutant discharge from the drainage basins of the Burnett Mary Region, Great Barrier Reef

TropWATER Report 14/32 Jon Brodie and Stephen Lewis

Ecologically relevant targets for pollutant discharge from the drainage basins of the Burnett Mary Region, Great Barrier Reef

TropWATER Report 14/32

Prepared by Jon Brodie and Stephen Lewis

Centre for Tropical Water & Aquatic Ecosystem Research

(TropWATER)

James Cook University

Townsville

Phone : (07) 4781 4262

Email: [email protected]

Web: www.jcu.edu.au/tropwater/

Information should be cited as:

Brodie J., Lewis S. (2014) Ecologically relevant targets for pollutant discharge from the drainage basins of the Burnett Mary Region, Great Barrier Reef. TropWATER Report No. 14/32, Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER), James Cook University, Townsville, 41 pp.

For further information contact:

Catchment to Reef Research Group/Jon Brodie and Steven Lewis

Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER)

James Cook University

ATSIP Building

Townsville, QLD 4811

[email protected]

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Acknowledgments:

Funding for this project came from the Burnett Mary Regional Group from funding provided by the Australian Government Department of the Environment. We acknowledge the help of our colleagues Ryan Turner, Katharina Fabricius, Scott Wooldridge, Geoff Park and Mel Shaw who assisted with data sets and suggestions about analysis.

Executive summary

Ecologically Relevant Targets

Ecologically relevant targets (ERT) attempt to define the pollutant load reductions that would be required to meet the GBR Water Quality Guidelines, which are set at a standard considered to be suitable to maintain ecosystem health. Thus ERTs are required to be met to achieve the overall long- term Reef Plan goal of “To ensure that by 2020 the quality of water entering the reef from broadscale landuse has no detrimental effect on the reef’s health and resilience”. The Reef Plan 2013 Targets (RPTs) are not set to achieve this overall goal. ERTs have been set for all the basins in the Burnett Mary region, for the main pollutants addressed in the Reef Plan 2013 targets. Both sets of targets, Reef Plan 2013 targets for 2018 and ERTs, are shown in Table E1.

The methods for deriving the ERTs vary between the pollutants. These are summarised below, and described in detail in the body of this report.

Total Suspended Sediments and particulate nitrogen and phosphorus targets

Ecologically relevant targets for suspended sediments are derived from understanding the impacts of sedimentation and turbidity on coral communities and seagrass meadows, and the relationships between end of catchment loads and turbidity in the receiving environment. The suspended sediment of most risk to the GBR is the fine fraction sometimes defined as that smaller than 15.6 μm, i.e. below the fine silt boundary and containing the clay and fine silt fractions (Bainbridge et al., 2012, 2014; Bartley et al., 2014) or of even more risk, just the clay fraction <4 μm. This is the component which contains most of the nitrogen and phosphorus content (and other contaminants), travels widely in flood plumes rather than all depositing near the river mouth (Lewis et al., 2014) and drives increased turbidity on the inner-shelf of the GBR (Fabricius et al. 2013, 2014; Logan et al. 2013, 2014). This increased fine sediment supply and hence increased turbidity and sedimentation can have severe impacts on GBR organisms such as reef fish (e.g. Wenger et al., 2011), corals (e.g. Weber et al., 2012; Flores et al., 2012) and seagrass (Collier et al., 2012, Petus et al., 2014). Resuspension of sediment in windy conditions or strong tidal currents in shallow waters (<15 m) leads to conditions where suspended sediment concentrations are above the GBR water quality guidelines (De'ath and Fabricius, 2008; Great Barrier Reef Marine Park Authority, 2010), and this threatens coral reefs and seagrass meadows through reduced light for photosynthesis (Bartley et al. 2014).

Using this knowledge of ecological relevance and factoring in the availability of data, suspended sediment targets for reduction of the < 4μm fraction have been set. Numerical results are available for this fraction for relevant rivers from the GBR Catchment Loads Monitoring Program (e.g. Turner et al., 2013). In the future it would be desirable to shift this criterion to <15.6 μm to better reflect ecological relevance. This will increase the target for reduction in total suspended sediment above the figures in the current ERTs.

The actual targets are derived from the analysis of the relationship between photic depth and river discharges in the region (Fabricius et al., 2014; Logan et al. 2014). The analysis shows a linear relationship between reduced fine sediment, particulate nitrogen (PN) and particulate phosphorus

(PP) and PP loads and increased Secchi depth (measured as photic depth) and indicates that a 50% reduction of the fine sediment fraction will be sufficient to generally meet the GBRMPA guidelines for Secchi depth (and thus SS concentrations) for coastal waters. A reduction of 50% of the <4 μm load corresponds to varying overall reductions in TSS load for each river (normally in the range 10 – 25% reduction).

Dissolved inorganic nitrogen targets

To determine ecologically relevant DIN targets for Burnett Mary rivers we are applying the ChloroSim model results (Wooldridge et al. 2006) by analogy. ChloroSim is specifically set up with reasonable data to model the required reductions in the Wet Tropics Rivers and Burdekin River. Results for the Wet Tropics WQIP which include an element of crown of thorns starfish (COTS) risk associated with DIN are typically between 50 – 70% reductions required for individual rivers. Given the model is not able to be specifically run in BM for lack of data we have assessed ERTs for BM rivers for DIN to be at the lower end of the range for the Wet Tropics as the additional COTS risk is not present in this Region. Thus we have set the ERT for DIN to be 50% for all BM rivers. Considerable further research is needed so as to be better able to apply the methodology in the BM region.

PSII herbicides targets

The photosystem-II inhibiting herbicides are currently the main pesticides of concern in the Great Barrier Reef (and are thus the only ones specifically addressed in Reef Plan) and concentrations have been detected that are likely to cause negative effects in the freshwater, estuarine and marine environments. A new set of ecotoxicity threshold values have recently been proposed for marine environments (Smith et al., in prep) which have been developed to revise and update the Australian and New Zealand Water Quality guidelines. These proposed marine threshold values are available for the PSII herbicides diuron, atrazine, ametryn, hexazinone and tebuthiuron (and the insecticide imidacloprid) and have been derived using the latest ecotoxicological data and statistical techniques. It is likely that these guidelines will be adopted for the Great Barrier Reef Marine Park in place of the current GBRMPA (2010) values and are thus used in setting ERTs for these PSII herbicides in the Burnett Mary. We use the 99% ecological protection values for Australian marine environments at the end of river systems in the Burnett Mary basins as (1) The 99% level of protection is in accordance with the current GBRMPA (2009) guideline’s recommendations and (2) if the guideline is met at the end of the river then this ensures that no part of the Marine Park (or waters south of the GBRMP boundary) is negatively affected by a particular herbicide.

While the herbicide concentrations are of most importance to gauge their risk to receiving waters, the Reef Plan targets revolve around annual load reductions. Furthermore Reef Plan targets do not consider the ‘toxic load’ (i.e. the herbicides are considered of equal toxicity, although this is known to be not the case). Hence to develop ERTs we normalise the PSII herbicide loads to better reflect their toxic effects and then examine the reductions required to ensure that herbicide concentrations will remain below these ecologically relevant threshold concentrations. To do this we updated the Lewis et al. (2011) model with new monitored load data to produce the individual herbicide load estimations for the Burnett Mary basins. We calculated a PSII equivalent ‘toxic’ load using the proposed guideline values. We then used the predicted PSII normalised (to diuron) ‘first flush’ concentration and the diuron ecotoxicity value (0.08 µg.L-1) to examine the likely reduction required

5 to the end-of-basin loads so that the PSII herbicide concentrations would remain below these values. This analysis suggests that basins of the Burnett Mary require reductions in toxic PSII loads, i.e. the ERT to achieve the guideline values (Table 9), of between zero and 64% with the Baffle and Mary at zero, the Burrum at 20%, the Kolan at 51% and the Burnett at 64%.

While we have provided an ERT based on a load reduction, the guideline concentration (e.g. 0.08 µg.L-1 for diuron equivalent) should be adopted as the actual ERT. Currently, the guideline is expressed as a single concentration for each level of species protection but in future this needs to be associated with an exposure period (e.g. 48 hours or 72 hours). We have calculated a load ERT based on an EMC of a ‘first flush’ which roughly corresponds to a 72 hour period. Our current load reduction estimates are likely conservative as they encompass the total annual load rather than just the first flush load.

Table E 1. Summary of pollutant load reduction targets for basins in the Burnett Mary region. The table shows two sets of targets: Reef Plan Targets (RPT) and Ecologically Relevant Targets (ERT) for Total Suspended Solids (TSS), Dissolved Inorganic Nitrogen (DIN), Particulate Nitrogen (PN), Dissolved Inorganic Phosphorus (DIP), Particulate Phosphorus (PP) and PSII Herbicides (PSII). The derived Reef Plan (RPT) and Ecologically Relevant (ERT) Targets for the Burnett Mary Region rivers are shown as reductions in anthropogenic loads.

River Baffle Kolan Burnett Burrum Mary SS RPT 20% 20% 20% 20% 20% SS ERT actual 50% reduction 50% reduction 50% reduction 50% reduction 50% reduction in < 4 µm SS in < 4 µm SS in < 4 µm SS in < 4 µm SS in < 4 µm SS SS ERT 22% in total SS 22% in total SS 22% in total SS 22% in total SS 22% in total SS modelable DIN RPT 50% 50% 50% 50% 50% DIN ERT 50% 50% 50% 50% 50% PN RPT 20% 20% 20% 20% 20% PN ERT 50% 50% 50% 50% 50% PP RPT 20% 20% 20% 20% 20% PP ERT 50% 50% 50% 50% 50% DIP RPT 0 0 0 0 0 DIP ERT 50% 50% 50% 50% 50% PSII RPT 60% 60% 60% 60% 60% PSII ERT 0 51% 64% 20% 0

1. Introduction

Riverine pollutant loads to the GBR lagoon have increased substantially since European settlement, with published estimated increases of up to 6-fold for suspended sediment (SS), 6-fold for nitrogen, and 9-fold for phosphorus (Kroon et al. 2012). The modeled average annual load of six widely used photosystem II inhibiting herbicides (atrazine, tebuthiuron, simazine, ametryn, diuron and hexazinone) is estimated to be 17,000 kilograms, however, this is likely to underestimate the total pesticide load, as at least 34 pesticides have been detected in waterways that discharge to the GBR (Brodie et al. 2013a). More recent results from the Source Catchments (SCM) modelling program within the Paddock to Reef Monitoring and Modelling Program (Carroll et al. 2012; Waters et al.

2013, 2014) have produced smaller estimates of increases above pre-European viz 2.8 times increase for SS, 2 times for dissolved inorganic nitrogen (DIN), 2 times for dissolved inorganic phosphorus (DIP), 3 times for particulate phosphorus (PP) and 2 times for particulate nitrogen (PN). These estimates (Waters et al. 2014) have been used in our process to derive targets described below. The main source of excess nutrients, fine sediments and pesticides is agricultural land use, with increased loads of (i) fine sediment and particulate nutrients primarily derived from erosion in rangeland grazing and cropping lands; (ii) dissolved inorganic nutrients, particularly nitrogen, associated with fertilizer applications in cropping land uses such as sugarcane, horticulture and broad acre cropping; and (iii) pesticides (particularly herbicides) primarily sourced from sugarcane cultivation and grazing lands (Brodie et al. 2012, 2013a; Thorburn et al. 2013; Waterhouse et al. 2012).

End-of-system load targets for the major pollutants addressed in Reef Plan 2009 were set for the entire Great Barrier Reef in Reef Plan 2009 (Queensland Government 2009). The targets are shown in Table 1. In addition load targets were set within the Reef Rescue initiative in 2008 (Brodie et al. 2012) as also shown in Table 1. The two sets of targets are loosely linked although internally inconsistent. Both sets of targets were set on the basis of what could be achieved through ‘feasible’ agricultural management change to ‘better’ management practices of the Great Barrier Reef Catchment (GBRC) (Brodie et al. 2012). Neither set of targets were set on the basis of ecological realities for the Great Barrier Reef (GBR) although attempts to design targets of this type have been made (e.g. Brodie et al. 2009). There is no guarantee that the Reef Plan 2009 targets will lead to the overall Reef Plan objective of “To ensure that by 2020 the quality of water entering the reef from adjacent catchments has no detrimental impact on the health and resilience of the Great Barrier Reef”. A new set of targets were set for Reef Plan 2013 (Table 2) (Queensland Government 2013).

Table 1. Reef Plan (2009) and Reef Rescue (2009) targets. Reef Rescue targets shaded

Target Scale (area) for Reporting reporting frequency 50% Reduction in N load at EOC by 2013 EOC for all GBR Annual catchments 50% Reduction in P load at EOC by 2013 EOC for all GBR Annual catchments Reduce the load of dissolved nutrients from agricultural lands to EOC for all GBR Annual the GBR lagoon by 25% by 2013 catchments Reduce the discharge of particulate nutrients from agricultural EOC for all GBR Annual lands to the GBR lagoon by 10% by 2013 catchments 50% Reduction in pesticide load at EOC by 2013 EOC for all GBR Annual catchments Reduce the load of chemicals from agricultural lands to the GBR EOC for all GBR Annual lagoon by 25% by 2013 catchments

Target Scale (area) for Reporting reporting frequency Minimum 50% late dry season groundcover in DT grazing lands Sub catchment for Annual by 2013 Burdekin and Fitzroy. 20% Reduction in sediment load by 2020 EOC for all GBR Annual catchments Reduce the discharge of sediment from agricultural lands to the EOC for all GBR Annual GBR lagoon by 10% by 2013 catchments No net loss or degradation of wetlands Catchment for all Yr 1 and 5 GBR catchments Condition and extent of riparian areas improved Catchment for all Yr 1 and 5 GBR catchments 80% of landholders adopted improved practices Sub catchment or Annual catchment by sector To increase the number of farmers who have adopted land Sub catchment or Annual management practices that will improve the quality of water catchment by sector progress; major reaching the reef lagoon by a further 1300 over 3 years report 2011 50% of landholders adopted improved practices (grazing) Sub catchment or Annual catchment To increase the number of pastoralists who have improved Sub catchment or Annual ground cover monitoring and management in areas where runoff catchment progress; major from grazing is contributing significantly to sediment loads and report 2011 a decline in the quality of water reaching the reef lagoon by a further 1500 over 3 years

Table 2. Reef Pan 2013 Targets

Water quality targets (2018)

• At least a 50 per cent reduction in anthropogenic end-of-catchment dissolved inorganic nitrogen loads in priority areas.

• At least a 20 per cent reduction in anthropogenic end-of-catchment loads of

sediment and particulate nutrients in priority areas.

• At least a 60 per cent reduction in end-of-catchment pesticide loads in priority areas.

Land and catchment management targets (2018)

• 90 per cent of sugarcane, horticulture, cropping and grazing lands are managed using best management practice systems (soil, nutrient and pesticides) in priority areas.

• Minimum 70 per cent late dry season groundcover on grazing lands.

• The extent of riparian vegetation is increased.

• There is no net loss of the extent, and an improvement in the ecological processes and environmental values, of natural wetlands.

The possibility of reaching the overall goal of Reef Plan (see above) of ‘no detrimental impact’ is also in question given that current ‘Best Management Practices’ may not be enough to achieve this outcome (Kroon, 2012; Thorburn and Wilkinson, 2013). Modeling of land-use adoption scenarios across the entire GBR has shown that complete adoption of current best management practices in grazing and sugarcane would be sufficient to meet the Reef Plan targets for photosystem II herbicides, but are uncertain for suspended sediment, nitrogen and phosphorus (Thorburn and Wilkinson 2013; Waters et al. 2013) and the desired ecological outcomes (Kroon 2012).

2. Changes in the targets between 2009 and 2013.

Large changes in many of the targets were made in Reef Plan 2013. In particular greatly relaxed targets were set for nitrogen and phosphorus while the sediment target remained unchanged and a small tightening of the pesticide target resulted (from 50% reduction in loads to 60% reduction). In Table 4 we have calculated the changed nitrogen and phosphorus targets resulting from the changes made between Reef Plan 2009 and Reef Plan 2013. This calculation involved using the percentages of PN to DIN to DON in the Source Catchments estimates for the whole GBR discharge (Waters et al. 2014) and that a reasonable interpretation of the Reef Plan 2013 target of:

• At least a 50 per cent reduction in anthropogenic end-of-catchment dissolved inorganic nitrogen loads in priority areas.

• At least a 20 per cent reduction in anthropogenic end-of-catchment loads of sediment and particulate nutrients in priority areas. meant a 50% reduction in DIN, a 20% reduction in PN and no reduction in DON with ‘priority areas’ ignored (as they are not clearly defined in Reef Plan 2013) in favour of ‘all the GBR catchment (GBRC)’.

Similarly for phosphorus we interpreted the Reef Plan 2013 targets of:

• At least a 20 per cent reduction in anthropogenic end-of-catchment loads of sediment and particulate nutrients in priority areas. meant no reduction in DIP, a 20% reduction in PP and no reduction in DOP across the GBRC.

From these calculations we estimate that in 2009 a 50% reduction in TN load was required whereas in 2013 we estimate a 36% reduction is all that is required. Similarly for TP, in 2009 a 50% reduction was required whereas in 2013 only a 16% reduction is required. These changes will have consequences in reporting progress towards targets as the targets are now much ‘easier’.

In Table 3 we estimate current targets for the various parameters. In each case the final target is the current load minus the reduction required under the Reef Plan targets.

Table 3. Targets calculated for the 2009 and 2013 Reef Plans using SCM current load estimates

Parameter Pre- Current Anthropogenic Load reduction New target European load (CL) load (AL) required (LR) = CL - LR (PE) (tonnes) loads (tonnes) Reef Plan 50% 2009 TN 19,000 37,000 18,000 9,000 28,000 TP 2,500 6,300 3,800 1,900 4,400

Reef Plan 20% PN, 50% 2013 DIN, 20% PP, 0% DIP PN 3,500 12,000 8,500 1,700 10,300 DIN 500 10,000 9,500 4,750 5,250 DON 14,000 14,000 0 0 14,000 Thus TN 19,000 37,000 18,000 6,450 (36% of 30,550 Anthropogenic load) PP 1,300 4,400 3,100 620 3,580 DIP 600 1,300 700 0 1.300 DOP 600 600 0 0 600 Thus TP 2,500 6,300 3,800 620 (16% of 5,680 Anthropogenic load)

3. Stage One targets based on Reef Plan targets (not ecologically based) for individual GBR basins

The current Reef Plan targets apply to the total catchment area of the GBR and total discharge from this GBR Catchment (GBRC). Thus there are no targets for individual river basins or NRM regions. The different basins across the GBRC vary greatly in their degree of development and hence relative magnitude of anthropogenic loads of pollutants and potential ‘risk’ posed to the GBR (Waterhouse et al. 2013). The Lockhart Basin on Cape York has little development of intensive land uses and as a result anthropogenic loads of all the pollutants are almost zero. In contrast the Tully Basin is highly developed and anthropogenic loads of all pollutants are large. For investigation of priority reductions needed for individual basins, a first step beyond GBR wide targets is required to develop the Reef Plan targets at the basin scale. As a first step for WQIP purposes we have developed individual basin targets based on the 2013 set targets. We have used targets (for 2018) of a 20% overall reduction in anthropogenic suspended sediment load; a 20% reduction in anthropogenic loads of particulate nitrogen (PN) and particulate phosphorus (PP); 50% reduction in anthropogenic loads of dissolved inorganic nitrogen (DIN); zero reduction in anthropogenic loads of dissolved inorganic phosphorus (DIP) and 60% reductions of loads of PSII herbicides. The PSII herbicides considered are hexazinone, ametryn, atrazine, diuron and tebuthiuron.

Our first method penalized, in a proportional way, basins with the largest increases in delivery of that pollutant over pre-European load. We considered that the targets obtained this way (Target method 1) to be unrealistic as in several cases targets lower than the pre-European loads were set. This is due to the method doubly penalizing basins with large increases above pre-European loads as it works on anthropogenic loads, not total loads. So the final method adopted (Target method 2) requires load reductions equal to the overall reduction target for the GBR applied to anthropogenic loads i.e. the target for DIN at the GBR scale is 50% reduction in anthropogenic load, hence the target for DIN reduction in the Tully Basin is also 50% of the anthropogenic load. For basins with no anthropogenic load e.g. DIN in the Olive-Pascoe the target is still 50% reduction, but 50% of zero is 0 tonnes. This method still produces confronting absolute load reduction targets but does distribute the required reductions in a proportional way, in terms of the increased loads that have occurred due to development of the individual basins, across the GBR catchment.

The calculation method to get to the new target in all cases is as follows using DIN in the Fitzroy Basin as an example.

Current total DIN load = 1106 tonnes. Anthropogenic DIN load = 475 tonnes. 50% reduction (the target) in anthropogenic load of 475 = 237.5 tonnes to be reduced. Thus target total load = 1106 (current total) – 237.5 (amount to be reduced) = 868 tonnes.

For the Water Quality Improvement Plan process in the Burnett Mary we have chosen to use the following set of targets for the Reef Plan 2013 derived targets out of those estimated above:

SS – 20% reduction (but see ecologically relevant Stage 2 targets discussed below)

PN – 20% reduction (but see ecologically relevant Stage 2 targets discussed below)

PP – 20% reduction (but see ecologically relevant Stage 2 targets discussed below)

DIN – 50% reduction

PSII herbicides – 60% reduction

There are no targets for DIP, DON or DOP.

4. Stage two ecologically relevant targets based on particle size – nutrient content relationships

Discussion of sediment particle size made in this section follow the Udden–Wentworth size classification for sand (>63 μm), medium and coarse silt (16–63 μm), fine silt (4–16 μm) and clay (<4 μm) (Leeder, 1982). These size classes, although standard, are often augmented with additional class fractions to represent specific processes in fluvial or marine systems. For example, the 10 μm threshold, or sortable silt fraction, is used in oceanography to distinguish silt sizes <10 μm that behave differently under wave and current processes (McCave et al., 1995). Silt <10 μm generally behaves in the same way as clay, and silt <10 μm responds more readily to hydrodynamic processes offshore. Therefore the sortable silt fraction is often referred to in publications describing sediment transport processes in the near-shore zone (e.g. Orpin et al., 1999).

The suspended sediment of most risk to the GBR is the fine fraction sometimes defined as that smaller than 16 µm i.e. below the fine silt boundary and containing the clay and fine silt fractions (Bainbridge et al. 2012, 2014; Bartley et al. 2014; Brodie et al. 2013b) or of even more risk just the clay fraction < 4 µm . This is the component which contains most of the nitrogen and phosphorus content (and other contaminants), travels widely in flood plumes rather than all depositing near the river mouth (Lewis et al. 2014) and drives increased turbidity on the inner-shelf of the GBR (Fabricius et al. 2013, 2014). This increased fine sediment supply and hence increased turbidity and sedimentation has severe impacts on GBR organisms such as reef fish (Wenger et al. 2011, 2012, 2013, 2014), corals (e.g. Weber et al. 2006, 2013; Flores et al. 2013) and seagrass (Collier et al. 2012, Petus et al. 2014).

Some coral species can tolerate very high sedimentation rates (Sofonia and Anthony, 2008) and turbidity (Browne et al., 2012), and recovery from short-term or low levels of sedimentation has been observed (Philipp and Fabricius, 2003; Wesseling et al., 1999). However, most corals reliant on autotrophy through zooxanthellae are negatively affected by smothering (sedimentation) and reduced light availability for photosynthesis due to turbidity in the water column (Dubinsky and Stambler, 1996; Fabricius, 2011).

Sedimentation:

Flores et al. (2012) comprehensively reviewed the lethal and sub-lethal effects of chronic exposure of corals to fine sediments and highlighted that particulate matter settling onto the coral cause stress as the process of sediment rejection leads to down-regulation of photosynthesis and increased rates of respiration and mucous production. The level of stress is related to particle size, organic content and nutrient composition of the sediment. With increasing exposure to sediments, coral growth rates decline, symbionts are known to be expelled (bleaching), and tissue loss occurs. Sedimentation also negatively affects rates of gamete fertilization and survival and settlement of

12 coral larvae (Flores et al., 2012). High sedimentation rates may reduce larval recruitment, making the settlement substratum unsuitable (Dikou and van Woesik, 2006; Hodgson, 1990). Particle size and organic and nutrient-related sediment properties are key factors determining sedimentation stress in corals (Philipp and Fabricius, 2003; Weber et al., 2006, 2012) due to microbial processes leading to reduced oxygen and the formation of toxic hydrogen sulphide. The nutrient enhanced sediments are known to form ‘muddy marine snow’ which can have detrimental impacts on corals within 1 h of settling (Fabricius and Wolanski, 2000). De'ath and Fabricius (2008) suggest that a daily maximum sedimentation rate of 15 mg cm−2 d−1 or a mean annual rate of 3 mg cm−2 d−1 as ecologically relevant values that should guard against excessive coral mortality. These values equate to average suspended sediment concentrations of 1.6 mg L−1 in winter and 2.4 mg L−1 during the summer wet season and have been adopted into GBRMPA water quality guidelines (GBRMPA, 2010).

Turbidity:

Growth of adult corals, seagrass and macroalgae is inhibited through reduced light caused by reduced water clarity. Sediment resuspension in windy conditions or strong tidal currents in shallow waters (<15 m) leads to conditions where TSS concentrations are above the GBR water quality guidelines (De'ath and Fabricius, 2008; GBRMPA, 2010). Reduced water clarity leads to changes in the distribution of seagrasses to shallower waters (Collier et al., 2012). For coral reef systems reduced water clarity has been associated with increased macroalgal cover, reductions in coral biodiversity (De'ath and Fabricius, 2010), increased macro-bioeroder densities (LeGrand and Fabricius, 2011), and a shift from communities dominated by phototrophic corals to heterotrophic filter feeders (Birkeland, 1988). However, some coral reefs have developed and thrived in nearshore areas with high turbidity (Browne et al., 2012; Palmer et al., 2010).

For strong ecological relevance we will choose to set targets for reduction of the < 15.6 µm particle size fraction. This fraction of the SS load forms organic rich flocs in the flood plumes (Bainbridge et al. 2012) which are transported 100s of km from the river mouth. Figures 1, 2 and 3 show river flood plumes from the Burdekin, Burnett Mary and Wet Tropic regions respectively where the inner plume is dominated by coarser sediment fractions (muddy brown material near the river mouth) and the further reaches of the plume dominated by the fine sediment fractions (< 15.6 µm) and algal blooms. Hence this finer sediment fraction (<15.6 µm) is considered to be the most important component of the total suspended sediment load in terms of risk to Great Barrier Reef ecosystems (Bainbridge et al., 2012).

Figure 1. The progression of the Burdekin River plume from a muddy brown material near the river mouth to an organic rich green material by Magnetic Island can be seen. Plumes from the Mary and Burnett Rivers exhibit the same behaviour (Figure 2) as do those from the Wet Tropics rivers (Figure 3).

Figure 2. Burnett and Mary Rivers plumes 2011

Figure 3. Plumes from the Russell-Mulgrave, Barron and Daintree/Mossman Rivers

Currently we only have particle size distribution for river discharge sediment at < 4 µm and <63 µm fractions from the GBR Catchment Loads Monitoring Program (e.g. Turner et al. 2013). Hence we will have to use the < 4 µm particle size fraction to develop our ERTs as these are the only quantifiable data that exist. We note by using the < 4 µm particle size fraction will give a conservative estimate on the SS load reduction targets. In Table 4 we have modified Figure 7.24 from Turner et al. (2013) showing the proportions of the size classes of suspended sediment found in 11 rivers in the GBRC. Details of the methodology of the methods can be found in Turner et al. (2013).

Table 4. Particle size fractions (%) from selected large rivers (modified from Turner et al. 2013) Particle Normanby Barron Johnstone Tully Herbert Burdekin Pioneer Fitzroy Burnett fraction (up river site) Coarse 0.4 4 0.2 0.4 0.6 0.6 0.8 0.8 0.5 sand 2000 – 250 µm Fine sand 0.4 6 9 4 7 4 5 0.8 2 62 – 250 µm Silt 4 – 62 47 66 75 66 70 50 70 38 53 µm Clay 0.24 52 24 15 29 22 46 25 60 45 – 4 µm

The slopes of the relationship between photic depth and river discharges examined initially in the Burdekin region (Fabricius et al. 2014; Logan et al. 2013) suggests that annual mean photic depth across the shelf was reduced by 1.7% for each 1000 t of TP discharged into the GBR, or by 0.47% for each 1000 t of TN. Figure 4 shows the relationship between river discharge of TN versus photic depth. We use TN to analysis this relationship as it’s serves as a good proxy (as does TP) for the fine sediment fraction. River discharge of total SS (TSS) gives a much poorer correlation as TSS is not a good proxy for just the fine fraction (< 15.6 µm)(Logan et al. 2013, 2014).

We use the coastal zone band (Figure 5) for our correlation analysis although similar relationsips apply in inshore and lagoon bands (Figure 5,7).

Figure 4. Relationship between log TN and photic depth.

Figure 5. The GBR cross-shelf water quality bands (Fabricius et al. 2014).

Predicted annual mean photic depth would also increase by 4.8%, 5.9%, 5.3% and 3.5% in the coastal, inshore, lagoon and midshelf bands for a 50% reduction in TP loads in the Burdekin River (Fabricius et al. 2014). These gains would be unevenly distributed across the year, with gains exceeding the annual means from February to July, and smaller benefits in the remaining months. Although a 50% reduction may appear substantial, it is a relatively modest goal compared with the ~6-fold increases of TP since pre-European times (Kroon et al., 2012). The model predicts similar gains for a 50% reduction in TN (4.1%, 5.5%, 4.7% and 2.9%) (Figure 6), but annual mean values of TP and TN are highly correlated (R2 = 0.94), making it impossible to asses the relative merits of using either parameter as both the best proxy for fine sediment and as a measure of the actual effects of the nutrient contained in the fine sediment. Strong interactive effects between dissolved nutrients and fine sediments, through the formation of organic rich flocs that remain easily resuspendible (Bainbridge et al., 2012), further highlight the difficulty to separating the relative effects of specific forms of nutrients and sediments.

Figure 6. Increased photic depth as a result of reduced fine sediment and particulate nutrient inputs

The relationship between discharge and clarity is seen in Figure 4 for the Burdekin River. Relationships are similar for the southern rivers of the GBR (Figure 7) and the results of these studies are now in report form. Note the Burnett Mary rivers were not included (at this stage) in these studies. However given the uniform behavior across the rest of the GBR we are confident the same relationships apply in the Burnett Mary region.

Given for the Burnett River, for example, the < 4 µm fraction is 45% of the total then a reduction of 50% of this fraction corresponds approximately to a 22% reduction in the TSS load. So our ecologically relevant target in this river is a 22% reduction in TSS, manifested specifically as a 50% reduction in < 4 µm fraction load and also a ~ 50% reduction in PP and PN loads. As we only have particle size proportions for the Burnett, at this stage we will use the same proportion for all Burnett Mary rivers. This is likely to be in considerable error but has to be accepted until better data are available.

So our final ERT for SS in the Burnett Mary region are as below (Table 5) with a distinction made between what is the actual ERT and what is the equivalent load able to be modelled in SC and INFFER.

Table 5. ERTs for SS in BM region

Basin ERT Modelable ERT Baffle 50% reduction in < 4 µm 22% in total SS SS Kolan 50% reduction in < 4 µm 22% in total SS SS Burnett 50% reduction in < 4 µm 22% in total SS SS Burrum 50% reduction in < 4 µm 22% in total SS SS Mary 50% reduction in < 4 µm 22% in total SS SS

Figure 7. Correlations between photic depth and river loads in the southern GBR. (from Logan et al. 2014).

5. Ecologically relevant pesticide targets

Currently, it is considered that the photosystem-II inhibiting herbicides are the main pesticides of concern in the Great Barrier Reef and concentrations have been detected that are likely to cause negative effects in the estuarine and marine environment. Indeed, it is the concentration of a

21 particular herbicide that provides a measure of toxicity to non-target species. A new set of ecotoxicity threshold values have recently been proposed for marine environments (Smith et al., in prep) which have been developed to revise and update the Australian and New Zealand Water Quality guidelines. These proposed values are available for diuron, atrazine, ametryn, hexazinone, tebuthiuron and imidacloprid (Table 6) and have been derived using the latest ecotoxicological data and statistical techniques. It is the view that these guidelines will be adopted for the Great Barrier Reef Marine Park in place of the current GBRMPA (2010) values. We contend that the proposed 99% ecological protection values for Australian marine environments be adopted for the end of river systems in the Burnett-Mary Basins as (1) The 99% level of protection is in accordance with the current GBRMPA (2009) guideline’s recommendations and (2) if the guideline is met at the end of the river then this ensures that no part of the marine park is negatively affected by a particular herbicide. Further, Poggio et al. (2013) has developed a relative toxicity measure (to diuron), which we have used for herbicides commonly used in the Great Barrier Reef that currently have no official recognised value (Table 6). In the absence of additional data, we consider these values can be used as a first approximation guide to gauge potential effects in the Great Barrier Reef of these particular herbicides. We note that herbicide guideline values can also be derived for freshwater and estuarine environments and these are currently under development.

Table 6. Previous GBRMPA (2009) guideline value compared with the new proposed 99% Australian marine guideline (Smith et al., in prep) and a ‘derived guideline’ based on relative toxicity scores to diuron (Poggio et al., 2013). The bolded values are considered our best estimates for 99% protection of marine species.

Existing GBRMPA Proposed 99% ecotoxicity Derived guideline Herbicide (2009) guideline threshold (µg.L-1) (µg.L-1) (µg.L-1)

Diuron 0.9 0.08 0.08 Ametryn 0.5 0.02 0.08 Atrazine 0.6 2.8 0.53 Hexazinone 1.2 0.9 0.23 Tebuthiuron 0.02 4.3 N/A Imidacloprid N/A 0.03 N/A Metribuzin N/A N/A 0.67 S-Metolachlor N/A N/A 0.27 Pendimethalin N/A N/A 13 Isoxaflutole N/A N/A 0.06 Imazapic N/A N/A 0.05 Glyphosate N/A N/A 80 2,4-D 0.8 N/A 7.3 Fluroxypyr N/A N/A 20 Paraquat N/A N/A 40 Propazine N/A N/A 4.00

Trifloxysulfuron N/A N/A 0.002 sodium Asulam N/A N/A 1.14

While the herbicide concentrations are of most importance to gauge their risk to receiving waters, the Reef Plan targets revolve around annual load reductions. Furthermore, current targets and reported loads examine the total sum of photosystem-II inhibiting herbicides including diuron, atrazine, ametryn, hexazinone and tebuthiuron and do not consider the ‘toxic load’ (i.e. the herbicides are considered of equal toxicity, although from the ecotoxicity threshold values presented in Table 6 it can been observed that diuron is ~50 times more toxic than tebuthiuron). Hence there is a need to normalise the herbicide loads to better reflect their toxic effects and then examine the reductions required to ensure that herbicide concentrations will remain below these ecologically relevant threshold concentrations. Unfortunately the Source Catchments model currently only reports total PSII inhibiting herbicide loads and do not consider these herbicides individually or as a ‘toxic PS-II load’. In this regard, we updated the Lewis et al. (2011) model with new monitored load

data to produce the individual herbicide load estimations for the Burnett-Mary basins (Table 7). We calculated a PSII equivalent ‘toxic’ load using the proposed guideline values in Table 6. We note presently these are the best estimates of herbicide loads for the basins of the Burnett-Mary.

Table 7. Predicted annual herbicide loads for the Burnett Mary Basins using the updated Lewis et al. (2011) model and the PSII weighted load based on ecotoxicity threshold values.

PSII Ametryn Atrazine Diuron Hexazinone Tebuthiuron Basin Flow (ML/y) weighted (kg) (kg) (kg) (kg) (kg) (kg)

Baffle Creek 491,201 0 3 0 1 1 0

Kolan River 74,321 0 6 3 3 1 3

Burnett River 193,141 0 96 4 38 9 11

Burrum River 258,813 0 14 6 6 1 6

Mary River 1,400,239 0 64 2 25 1 6

We examined the relationship between diuron and atrazine loads in the Burnett River for the 2010/11 and 2011/12 water years. In the 2010/11 wet season, we noted that 10% of the diuron load was discharged from the river during only 2.5% of the annual flow in an early first flush event (October 2010). Based on these findings, we calculated a maximum ‘first flush’ concentration using the PSII normalised loads assuming these parameters (Table 8). Further investigation of this relationship is required for the monitored rivers of the Burnett-Mary to better refine these calculations and future studies should also examine all the herbicides used in the basins. We used the predicted PSII normalised (to diuron) ‘first flush’ concentration and the diuron ecotoxicity threshold value (0.08 µg.L-1) to examine the likely reduction required to the end-of-basin loads so that the PSII herbicide concentrations would remain below these values. This analysis suggests that the Kolan River and Burnett River Basins require a 50% or higher reduction in toxic PSII loads (predominately influenced by the diuron load) to achieve the guideline values.

Table 8. Estimated herbicide concentrations from ‘first flush’ events and the reductions likely required of the current loads to achieve concentrations below guideline values.

Peak PSII 10% 2.5% PSII flush Reduction diuron Basin Flow (ML/y) weighted of of -1 EMC (µg.L ) required concen (kg) load flow tration Baffle Creek 491,201 0 0 12,280 0.00 0% N/A Kolan River 74,321 3 0 1,858 0.16 51% N/A Burnett River 193,141 11 1 4,829 0.22 64% 0.14* Burrum River 258,813 6 1 6,470 0.10 20% N/A Mary River (Qld) 1,400,239 6 1 35,006 0.02 0% 0.07** *from Turner et al. (2012, 2013)

**M. Devlin (unpublished)

6. Ecologically relevant DIN targets

7. Targets based on Reef Plan 2013 by Method 2.

Table 9. TSS loads for the GBR basins (kt.y-1) - 20% reduction target (Reef Plan 2013)

% decrease of Pre- Total Anthropogenic Target Basin Name Target anthropogenic Development (08/09) load reduction load

Jacky Jacky 43 44 1 0.2 43 20% Olive Pa scoe 58 60 3 0.5 60 20% River Lockhart River 38 39 1 0.2 39 20% Stewart River 19 29 10 2.0 27 20% Normanby River 53 188 135 27.1 161 20% Jeannie River 18 27 9 1.7 25 20% Endeavour River 21 42 21 4.2 38 20% Daintree River 44 62 19 3.8 59 20% Mossman River 7 14 7 1.4 13 20% Barron River 42 92 50 10.0 82 20% Mulgrave-Russell 67 168 101 20.2 148 20% River Johnstone River 88 265 178 35.5 230 20% Tully River 46 110 64 12.8 97 20% Murray River 21 43 22 4.5 39 20% Herbert River 130 463 333 66.6 396 20% Black River 82 107 25 5.0 102 20% Ross River 84 110 26 5.2 105 20% Haughton River 104 261 157 31.4 230 20% Burdekin River 1027 3173 2,146 429.2 2744 20% Don River 153 325 171 34.3 290 20% Proserpine River 29 66 37 7.5 59 20% O'Connell River 48 156 108 21.6 134 20% Pioneer River 40 203 163 32.6 171 20% Plane Creek 34 85 51 10.2 75 20% Styx River 28 68 40 8.0 60 20% Shoalwater Creek 27 53 26 5.2 48 20% Water Park Creek 27 32 5 1.0 31 20% Fitzroy River 440 1,740 1,300 259.9 1480 20% Calliope River 16 44 28 5.6 39 20% Boyne River 3 11 8 1.6 9 20% Baffle Creek 20 50 30 6.0 44 20% Kolan River 2 11 9 1.8 9 20% Burnett River 3 24 21 4.2 20 20% Burrum River 7 24 17 3.5 21 20% Mary River 61 352 291 58.2 294 20% Total GBR 2,931 8,545 5,613 1,123 7,422

Table 10. DIN loads for the GBR basins (t.y-1) - 50% reduction target (Reef Plan 2013)

% decrease of Pre- Total Anthropogenic Target Basin Name Target anthropogenic Development (08/09) load reduction load

Jacky Jacky Creek 73 73 0 0.0 73 50% Olive Pascoe River 102 102 0 0.0 102 50% Lockhart River 59 59 0 0.0 59 50% Stewart River 35 36 2 0.9 36 50% Normanby River 138 139 1 0.6 138 50% Jeannie River 34 34 0 0.0 34 50% Endeavour River 46 48 3 1.3 47 50% Daintree River 323 387 64 31.9 355 50% Mossman River 55 107 52 26.1 81 50% Barron River 47 90 43 21.7 68 50% Mulgrave-Russell 438 695 258 128.8 567 50% River Johnstone River 506 1,360 854 426.9 933 50% Tully River 344 702 358 179.1 523 50% Murray River 166 288 122 60.9 227 50% Herbert River 535 807 272 135.9 671 50% Black River 37 86 48 24.2 62 50% Ross River 31 224 193 96.5 128 50% Haughton River 61 762 701 350.4 412 50% Burdekin River 576 1,436 860 430.1 1006 50% Don River 49 139 90 45.1 94 50% Proserpine River 65 220 155 77.6 143 50% O'Connell River 75 303 228 114.1 189 50% Pioneer River 45 222 177 88.5 133 50% Plane Creek 88 384 296 147.8 236 50% Styx River 38 38 0 0.0 38 50% Shoalwater Creek 45 45 0 0.0 45 50% Water Park Creek 54 54 0 0.1 54 50% Fitzroy River 1,057 1,106 48 24.2 1082 50% Calliope River 23 23 0 0.0 23 50% Boyne River 6 6 0 0.0 6 50% Baffle Creek 12 31 19 9.5 21 50% Kolan River 2 21 19 9.4 12 50% Burnett River 31 123 93 46.3 77 50% Burrum River 17 119 102 51.2 68 50% Mary River 60 260 200 100.0 160 50% Total GBR 5,274 10,532 5,258 2,629 7,903

Table 11. PN loads for the GBR basins (t.y-1) - 50% reduction target (Ecologically relevant) % decrease of Pre- Total Anthropogenic Target Basin Name Target anthropogenic Development (08/09) load reduction load Jacky Jacky Creek 169 171 2 0.9 170 50% Olive Pascoe River 221 227 5 2.7 224 50% Lockhart River 147 147 0 0.0 147 50% Stewart River 61 83 21 10.6 72 50% Normanby River 118 224 106 53.0 171 50% Jeannie River 62 75 12 6.2 68 50% Endeavour River 60 104 44 22.1 82 50% Daintree River 195 282 86 43.1 239 50% Mossman River 34 59 25 12.3 46 50% Barron River 66 182 116 57.8 124 50% Mulgrave-Russell 284 141.8 417 50% River 276 559 Johnstone River 340 1,144 804 402.1 742 50% Tully River 210 421 211 105.5 316 50% Murray River 97 159 62 31.2 128 50% Herbert River 319 1,038 719 359.7 679 50% Black River 146 177 31 15.5 161 50% Ross River 93 142 49 24.6 117 50% Haughton River 113 294 181 90.4 203 50% Burdekin River 1482 3224 1,742 871.2 2353 50% Don River 222 441 219 109.4 331 50% Proserpine River 97 130 33 16.4 114 50% O'Connell River 119 186 67 33.5 153 50% Pioneer River 90 298 208 104.0 194 50% Plane Creek 99 124 25 12.6 112 50% Styx River 25 60 35 17.3 42 50% Shoalwater Creek 9 25 16 8.1 17 50% Water Park Creek 8 18 10 5.0 13 50% Fitzroy River 233 1,035 802 400.8 634 50% Calliope River 11 34 23 11.5 23 50% Boyne River 2 10 8 4.0 6 50% Baffle Creek 63 105 42 21.2 84 50% Kolan River 8 22 14 6.8 15 50% Burnett River 19 38 20 9.8 29 50% Burrum River 27 64 37 18.7 45 50% Mary River 210 546 336 167.8 378 50% Total GBR 5,452 11,847 6,395 3,198 8,650

Table 12. PN loads for the GBR basins (t.y-1) - 20% reduction target (Reef Plan 2013) % decrease of Pre- Total Anthropogenic Target Basin Name Target anthropogenic Development (08/09) load reduction load

Jacky Jacky Creek 169 171 2 0.4 170 20% Olive Pascoe River 221 227 5 1.1 226 20% Lockhart River 147 147 0 0.0 147 20% Stewart River 61 83 21 4.2 78 20% Normanby River 118 224 106 21.2 202 20% Jeannie River 62 75 12 2.5 72 20% Endeavour River 60 104 44 8.9 95 20% Daintree River 195 282 86 17.3 264 20% Mossman River 34 59 25 4.9 54 20% Barron River 66 182 116 23.1 159 20% Mulgrave-Russell 276 559 284 56.7 503 20% River Johnstone River 340 1,144 804 160.8 983 20% Tully River 210 421 211 42.2 379 20% Murray River 97 159 62 12.5 147 20% Herbert River 319 1,038 719 143.9 894 20% Black River 146 177 31 6.2 170 20% Ross River 93 142 49 9.8 132 20% Haughton River 113 294 181 36.1 258 20% Burdekin River 1,482 3,224 1,742 348.5 2876 20% Don River 222 441 219 43.7 397 20% Proserpine River 97 130 33 6.6 123 20% O'Connell River 119 186 67 13.4 173 20% Pioneer River 90 298 208 41.6 257 20% Plane Creek 99 124 25 5.1 119 20% Styx River 25 60 35 6.9 53 20% Shoalwater Creek 9 25 16 3.2 22 20% Water Park Creek 8 18 10 2.0 16 20% Fitzroy River 233 1,035 802 160.3 875 20% Calliope River 11 34 23 4.6 30 20% Boyne River 2 10 8 1.6 8 20% Baffle Creek 63 105 42 8.5 97 20% Kolan River 8 22 14 2.7 19 20% Burnett River 19 38 20 3.9 35 20% Burrum River 27 64 37 7.5 57 20% Mary River 210 546 336 67.1 479 20% Total GBR 5,452 11,847 6,395 1,279 10,568

Table 13. DIP loads for the GBR basins (t.y-1) - 50% reduction target (Ecologically relevant ) % decrease of Pre- Total Anthropogenic Target Basin Name Target anthropogenic Development (08/09) load reduction load

Jacky Jacky Creek 11 12 1 0.3 12 50% Olive Pascoe River 16 17 1 0.7 17 50% Lockhart River 9 9 0 0.0 9 50% Stewart River 5 8 2 1.2 7 50% Normanby River 22 34 12 6.1 28 50% Jeannie River 5 6 1 0.6 6 50% Endeavour River 7 11 4 2.1 9 50% Daintree River 18 24 6 2.8 21 50% Mossman River 3 5 2 1.0 4 50% Barron River 5 12 7 3.6 9 50% Mulgrave-Russell 25 41 16 8.1 33 50% River Johnstone River 28 49 21 10.3 39 50% Tully River 19 33 13 6.7 26 50% Murray River 9 17 8 4.0 13 50% Herbert River 30 47 17 8.5 39 50% Black River 6 12 6 3.0 9 50% Ross River 5 35 30 14.9 20 50% Haughton River 10 74 64 31.8 42 50% Burdekin River 97 201 105 52.3 149 50% Don River 8 18 10 5.0 13 50% Proserpine River 12 36 24 12.0 24 50% O'Connell River 14 35 21 10.4 25 50% Pioneer River 8 17 9 4.4 13 50% Plane Creek 18 44 26 13.1 31 50% Styx River 7 8 0 0.1 7 50% Shoalwater Creek 9 9 0 0.0 9 50% Water Park Creek 10 10 0 0.0 10 50% Fitzroy River 225 245 20 10.2 235 50% Calliope River 4 4 0 0.0 4 50% Boyne River 1 1 0 0.0 1 50% Baffle Creek 3 7 4 2.0 5 50% Kolan River 1 4 3 1.5 2 50% Burnett River 10 14 4 2.1 12 50% Burrum River 5 12 7 3.4 8 50% Mary River 16 41 25 12.7 28 50% Total GBR 685 1,155 470 235 920

Table 14. PP loads for the GBR basins (t.y-1) - 50% reduction target (Ecologically relevant) % decrease of Pre- Total Anthropogenic Target Basin Name Target anthropogenic Development (08/09) load reduction load

Jacky Jacky Creek 21 22 1 0.5 22 50% Olive Pascoe River 28 31 3 1.3 29 50% Lockhart River 18 18 0 0.0 18 50% Stewart River 8 17 9 4.3 13 50% Normanby River 28 105 76 38.1 66 50% Jeannie River 10 16 6 3.1 13 50% Endeavour River 11 29 18 9.0 20 50% Daintree River 41 57 16 7.8 49 50% Mossman River 7 14 7 3.4 10 50% Barron River 23 67 43 21.5 45 50% Mulgrave-Russell 65 175 110 54.8 120 50% River Johnstone River 104 453 349 174.3 278 50% Tully River 44 110 66 33.0 77 50% Murray River 20 46 26 13.0 33 50% Herbert River 97 377 280 140.1 237 50% Black River 43 50 7 3.3 47 50% Ross River 23 33 10 4.9 28 50% Haughton River 47 159 113 56.3 103 50% Burdekin River 512 1,300 788 394.1 906 50% Don River 73 146 73 36.5 110 50% Proserpine River 28 44 16 7.8 36 50% O'Connell River 39 84 45 22.7 61 50% Pioneer River 27 93 66 33.1 60 50% Plane Creek 30 50 20 9.8 40 50% Styx River 12 29 17 8.6 21 50% Shoalwater Creek 3 10 7 3.4 7 50% Water Park Creek 4 6 2 1.1 5 50% Fitzroy River 145 687 542 271.0 416 50% Calliope River 8 21 13 6.7 15 50% Boyne River 1 4 4 1.8 3 50% Baffle Creek 25 44 19 9.4 34 50% Kolan River 3 9 6 3.2 6 50% Burnett River 8 18 10 5.0 13 50% Burrum River 8 27 19 9.3 17 50% Mary River 73 181 108 53.8 127 50% Total GBR 1,640 4,532 2,892 1,446 3,086

Table 15. PP loads for the GBR basins (t.y-1) - 20% reduction target (Reef Plan 2013) % decrease of Pre- Total Anthropogenic Target Basin Name Target anthropogenic Development (08/09) load reduction load

Jacky Jacky Creek 21 22 1 0.2 22 20% Olive Pascoe River 28 31 3 0.5 30 20% Lockhart River 18 18 0 0.0 18 20% Stewart River 8 17 9 1.7 15 20% Normanby River 28 105 76 15.3 89 20% Jeannie River 10 16 6 1.3 15 20% Endeavour River 11 29 18 3.6 26 20% Daintree River 41 57 16 3.1 54 20% Mossman River 7 14 7 1.3 12 20% Barron River 23 67 43 8.6 58 20% Mulgrave-Russell 65 175 110 21.9 153 20% River Johnstone River 104 453 349 69.7 383 20% Tully River 44 110 66 13.2 97 20% Murray River 20 46 26 5.2 40 20% Herbert River 97 377 280 56.0 321 20% Black River 43 50 7 1.3 49 20% Ross River 23 33 10 2.0 31 20% Haughton River 47 159 113 22.5 137 20% Burdekin River 512 1,300 788 157.6 1143 20% Don River 73 146 73 14.6 132 20% Proserpine River 28 44 16 3.1 41 20% O'Connell River 39 84 45 9.1 75 20% Pioneer River 27 93 66 13.3 80 20% Plane Creek 30 50 20 3.9 46 20% Styx River 12 29 17 3.4 26 20% Shoalwater Creek 3 10 7 1.3 9 20% Water Park Creek 4 6 2 0.4 6 20% Fitzroy River 145 687 542 108.4 579 20% Calliope River 8 21 13 2.7 19 20% Boyne River 1 4 4 0.7 4 20% Baffle Creek 25 44 19 3.8 40 20% Kolan River 3 9 6 1.3 8 20% Burnett River 8 18 10 2.0 16 20% Burrum River 8 27 19 3.7 23 20% Mary River 73 181 108 21.5 159 20% Total GBR 1,640 4,532 2,892 578 3,954

Table 16. PSII loads for the GBR basins (kg.y-1) - 60% reduction target (Reef Plan 2013) % decrease of Pre- Total Anthropogenic Target Basin Name Target anthropogenic Development (08/09) load reduction load

Jacky Jacky Creek 0 0 0 0.0 0 60% Olive Pascoe River 0 0 0 0.0 0 60% Lockhart River 0 0 0 0.0 0 60% Stewart River 0 0 0 0.0 0 60% Normanby River 0 3 3 1.6 1 60% Jeannie River 0 0 0 0.0 0 60% Endeavour River 0 0 0 0.0 0 60% Daintree River 0 235 235 141.1 94 60% Mossman River 0 150 150 90.1 60 60% Barron River 0 269 269 161.6 108 60% Mulgrave-Russell 0 1,482 1,482 888.9 593 60% River Johnstone River 0 1,861 1,861 1,116.5 744 60% Tully River 0 1,359 1,359 815.4 544 60% Murray River 0 862 862 517.1 345 60% Herbert River 0 2,378 2,378 1,427.0 951 60% Black River 0 14 14 8.4 6 60% Ross River 0 6 6 3.4 2 60% Haughton River 0 1,353 1,353 812.1 541 60% Burdekin River 0 632 632 379.3 253 60% Don River 0 85 85 51.1 34 60% Proserpine River 0 539 539 323.2 215 60% O'Connell River 0 1,027 1,027 616.3 411 60% Pioneer River 0 859 859 515.7 344 60% Plane Creek 0 1,519 1,519 911.2 607 60% Styx River 0 22 22 13.4 9 60% Shoalwater Creek 0 14 14 8.2 5 60% Water Park Creek 0 10 10 5.8 4 60% Fitzroy River 0 521 521 312.5 208 60% Calliope River 0 10 10 5.8 4 60% Boyne River 0 2 2 1.5 1 60% Baffle Creek 0 23 23 13.8 9 60% Kolan River 0 257 257 154.4 103 60% Burnett River 0 271 271 162.9 109 60% Burrum River 0 531 531 318.8 213 60% Mary River 0 445 445 267.0 178 60% Total GBR 0 16,740 16,740 10,044 6,696

8. Summary

Burnett-Mary load reduction scenarios

For the Burnett-Mary WQIP we have put the individual river Reef Plan targets, extracted from Tables 9 – 16 above, into single targets for each of the BM basins.

Table 17. Burnett River

Parameter Current total Anthropogenic Load Load Total Target load load component reduction reduction load (2008/09 requirement amount Source Catchments mean)

TSS tonnes 20,000 17,000 20% 3,400 16,600

DIN tonnes 121 90 50% (2013) 45 76

PN tonnes 97 78 20% (2013) 15.6 81 PP tonnes 38 30 20% (2013) 6 32 PS II kg 279 279 60% (Reef 168 112 Plan 2013)

Table 18. Mary River

Parameter Current total Anthropogenic Load Load Total Target load load component reduction reduction load (2008/09 requirement amount Source Catchments mean)

TSS tonnes 362,000 301,000 20% 60,300 302,000

DIN tonnes 271 211 50% (2013) 106 165

PN tonnes 697 487 20% (2013) 98 600 PP tonnes 225 152 20% (2013) 30 195

PS II kg 456 456 60% (Reef 274 183 Plan 2013)

Table 19. Baffle Creek

Parameter Current total Anthropogenic Load Load Total Target load load component reduction reduction load (2008/09 requirement amount Source Catchments mean)

TSS tonnes 56,000 36,000 20% 7,200 49,000

DIN tonnes 31 19 50% 9.5 21

PN tonnes 96 33 20% (2013) 6 90

PP tonnes 39 14 20% (2013) 3 36

PS II kg 24 24 60% (Reef 14 10 Plan 2013)

Table 20. Kolan River

Parameter Current total Anthropogenic Load Load Total Target load load component reduction reduction load (2008/09 requirement amount Source Catchments mean)

TSS tonnes 12,000 10,000 20% 2,000 10,000

DIN tonnes 22 20 50% 10 12

PN tonnes 31 23 20% (2013) 5 26

PP tonnes 10 7 20% (2013) 2 8

PS II kg 267 267 60% (Reef 160 107 Plan 2013)

Table 21. Burrum River

Parameter Current total Anthropogenic Load Load Total Target load load component reduction reduction load (2008/09 requirement amount Source Catchments mean)

TSS tonnes 25,000 18,000 20% 3,600 21,000

DIN tonnes 119 102 50% 51 68

PN tonnes 80 53 20% (2013) 11 69

PP tonnes 23 15 20% (2013) 3 20

PS II kg 530 530 60% (Reef 318 212 Plan 2013)

In Table 22 we summarise the Reef Plan and draft ecologically relevant total load targets for Burnett Mary rivers.

Table 22 The Reef Plan and draft ecologically relevant total load targets for Burnett Mary Rivers

River basin Baffle Kolan Burnett Burrum Mary SS( kt) (Reef 49 10 17 21 302 Plan) SS (ER) 50% 50% 50% 50% reduction 50% reduction reduction reduction of reduction of of < 4 um SS of < 4 um SS of < 4 um < 4 um SS < 4 um SS SS PN (RP) 90 26 81 69 600 PN (ER) 80 19 58 53 454 PP (RP) 36 8 32 20 195 PP (ER) 32 6 23 16 149 DIN (t) (RP) 21 12 76 68 165 DIN (ER) 21 12 76 68 165 DIP (RP) No reduction DIP (ER) 5 2 12 7 28 PSII (kg) (RP) 10 107 112 212 183 PSII 0% 69% 77% 49% 0% (ER)

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