WATER QUALITY AND FILTERING CAPACITY

IN THE MACQUARIE MARSHES

LEAH MCCARROLL

A thesis submitted in partial fulfillment of the requirements of the Bachelor of Science in Agriculture degree program

Faculty of Agriculture, Food and Natural Resources The University of Sydney

November 2007

Acknowledgements

The funding for this project, with out which I would not have been able to undertake this work, came from the Cotton CRC. Thank you.

I would like to offer sincere thanks to my supervisors Dr Angus Crossan and Professor Ivan Kennedy who showed me that science can help bridge the gap between agriculture, the environment and public perceptions. Thank you for all the time and effort you gave me so freely.

I would also like to acknowledge the help I received from Paco Sanchez-Bayo who undertook two long, hot sampling trips out of his own time to ensure that I had all the necessary samples, and could also enjoy my honeymoon. Thank you also to Mitch Burns who accompanied him on one of these trips, and who always had encouraging words when the challenges were mounting.

A huge Thank you must also go to Dr Bob Caldwell who assisted with all my sample analysis and kept me from crying in the corner when the computer equipment broke. Ross and Andrew at Agrisearch Analytical took the time to analyse my pesticide samples and deserve a great big thanks! Also to Iona Gyorgy who greatly assisted with the technical side of my project, thank you.

To my wonderful husband Daniel, a huge thanks for all the critiquing and for accompanying me on two sampling adventures. I couldn’t have asked for a better chauffeur.

Finally I would like to thank my parents and Ron and Pam Arthur for always supporting me and feeding and housing me on weekends. And of course to my co-hort: you guys kept me going and made me laugh, rather than cry at the insanities, so thank you!

1 Table of Contents Paper 1: Literature Review ______3 I. Introduction ______4 II. Retention and Removal Processes ______5 (1) Nutrient Removal ______5 (a) Microbial removal______6 (b) Plant removal ______6 (c) Phosphorus Retention ______7 (2) Pesticide removal______10 (a) Microbial degradation ______10 (b) Plant degradation______11 (c) Adsorption______11 III. The Macquarie Marshes ______13 (1) Biodiversity of the Macquarie Marshes ______14 (2) Regulation of flows to the Macquarie Marshes ______15 IV. Agriculture in the Macquarie Valley ______16 (1) Irrigated cotton production ______17 (2) Cattle production ______18 V. Competition for Water Resources ______18 VI. Degradation issues______24 (1) Nutrient levels ______24 (a) Potential source of Nutrients: Grazing ______27 (b) Potential source of Nutrients: Change of flow patterns______29 (2) Regulation ______30 (3) Pesticide contamination______31 VII. Conclusions ______33 Paper 2: Thesis ______34 I. Introduction ______35 II. Materials and Methods ______39 1. Sample Sites______39 3. Sample Preparation______41 4. Sample Analysis______41 1. Nitrogen ______41 3. Total Phosphorus ______44 4. Total load ______46 5. Pesticide Concentration ______47 III. Results ______48 2. Nitrogen______51 3. Orthophosphate ______51 4. Total Phosphorus______51 5. Total load ______55 IV. Discussion ______58 V. Future Research ______70 VI. Conclusions ______71 VII. References ______73

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Paper 1: Literature Review

FACTORS AFFECTING WETLAND FUNCTION IN THE MACQUARIE MARSHES Leah McCarroll Sciences Discipline, Faculty of Agriculture, Food and Natural Resources, University of Sydney, NSW 2006, Australia

Abstract

The increasing rate of waterway eutrophication globally has lead to the recognition of the importance of wetlands and their potential contribution to water quality. Many studies have reported on the nutrient removal capacity of wetlands, with magnitudes varying from 3-93%. This large range is related to the many variables associated with a wetland ecosystem and the complex interactions between plants, microorganisms and abiotic factors. These interactions and associated processes and rates are not widely agreed upon in the literature.

Plant and microbe species can remove nutrients and pesticides from the water column and from sediments. These are then removed from the system by chemical reactions or physical removal or alternatively retained and recycled. Adsorption reactions also contribute to nutrient removal from the water column and are recognized in the literature as a major removal pathway for phosphorus. Desorption however, can result from a disturbance and may cause a net release of nutrients. The literature on nutrient and pesticide removal and retention by wetlands is reviewed.

The Macquarie Marshes are a wetland in the north west of NSW that has been subject to pressure from agriculture for many years. The area of the marsh and the associated biodiversity has declined since the introduction of agriculture to the area. The history of agriculture in the area and the possible causes of degradation of the Macquarie Marshes are reviewed.

Recent studies show that the Marshes are not filtering nutrients from river water to the extent expected by a natural wetland. Nutrient levels exiting the system have regularly exceeded those entering and can exceed the ANZECC local trigger values. The contributions of erosion, resulting from cattle grazing within the marshes, and from continual low flows, after the regulation of the system, are reviewed as possible reasons for these nutrient levels.

This review also examines the competition for water resources between the key stake holders in the area. Water from the Macquarie River is shared between agricultural enterprises (mainly cattle and irrigated cotton production), town water supplies and the environment. The social and economic reliance on agriculture and the value and importance of the Macquarie Marshes must be taken into account when managing the water allocations of the Macquarie River.

Key words: Macquarie Marshes, Phosphorus, Nitrogen, Wetland, Nutrient removal, Agriculture, Water quality

3 I. Introduction

Wetlands provide a valuable habitat for birds and animals (Jenkins et al. 2005; Mathias and Moyle 1992) and support many plant species (Finlayson and Mitchell 1999; Kingsford and Thomas 1995; Lemly et al. 2000). Provision of habitat for native and migratory species is an important function of wetlands, particularly in arid countries such as Australia. In addition to this inherent value, wetlands commonly increase the value and quality of the water downstream and as such are often credited as filtering mechanisms. Wetlands mainly improve water quality by removing nutrients and sediments, recycling organic matter and providing a site for chemical degradation (Brady and Riding 1996). Constructed wetlands are becoming a recognized method of reducing pesticide concentrations in run off derived from agricultural areas (Schulz 2004). The potential for biological and chemical transformation is increased by the decreased flow rates and the increased plant and microbial biodiversity (Angier et al. 2002; Roberts 1998; Rose et al. 2006; Stangroom et al. 2000). Finlayson et al., (1986) report a decrease in pH, turbidity, electrical conductivity as well as nitrogen and phosphorus loads, with passage through a constructed wetland in Thredbo, NSW.

The Macquarie Marshes are a non terminal wetland located in the Macquarie valley of northwestern New South Wales (N.S.W.). The Marshes provide a habitat for numerous native birds and animals and are highly diverse in plant species. However, a complex mixture of anthropogenic stressors, including alteration of natural flow patterns, diffuse and point source inputs of nutrients and the loss of marsh vegetation has led to a highly stressed ecosystem. Although it appears that the Macquarie Marshes should act as a filtering mechanism, often the nutrient levels exiting the marshes exceed that entering the system. The area and biodiversity of the Marshes has also decreased, all of which has lead to concern for the ecosystem and calls for the rejuvenation of this highly valuable resource.

Inherent in the debate regarding the health of the Macquarie Marshes is the fact that agriculture in the area is a highly important industry socially and economically. Management of the system must therefore accept the challenge of this competition for resources, while achieving environmental sustainability.

4 II. Retention and Removal Processes

(1) Nutrient Removal

Picard (2005) states that eutrophication is the most significant water quality problem throughout the world. Excess nutrients can have many detrimental affects on waterways and surrounding ecosystems, and their removal by wetland areas is considered extremely important. Excess nitrogen and phosphorus can lead to algal blooms (Angier et al. 2002) and the occurrence of water borne bacteria, such as Pfeisteria piscicida (Buck et al. 1997). Blue green algae, a group of cyanobacteria, can have detrimental effects on ecosystem health and can produce toxins harmful to fauna and humans. As algal blooms senesce, decomposition reduces the dissolved oxygen of the waterways. Reduced levels of dissolved oxygen in the water column have serious effects on the aquatic system and can further degrade water quality (DLWC 1997).

Removal of nitrogen and phosphorus from treated wetlands can range from 3-93% (SpielesMitsch 2000), with the average rate of removal reported as 50% (Verhoevan and Meulman 1999). Finlayson et al. (1986) reported a reduction of nitrogen and phosphorus loads from waste water by 65% and 44% respectively after passage through a constructed wetland. Furthermore, Headley et al. (2003) reported a reduction in total phosphorus from 0.5 mg L-1 to 0.005 mg L-1

Wang & Mitsch (2000) attribute the efficiency of nutrient removal to the factors: low stream velocity, shallow water and high plant production, allowing maximum absorption and high levels of sedimentation. Picard (2005) however, suggests that a high diversity of plant species and increased ground cover are more important in terms of supporting nutrient removing microbial communities than direct removal of nutrients through absorption. White et al. (2004) recognized the interactions of the main removal pathways: surface adsorption to soil minerals, microbial immobilization, and plant uptake. This variability in the literature is common due to the limited understanding of removal and remediation processes, the vastly different plants, microbes, and climates of wetlands, in addition to the complex interactions between microbes and plants. The main biological methods of nutrient removal are rhizosphere remediation and plant uptake.

5 (a) Microbial removal Rhizosphere remediation is a result of microbial communities, and does not involve plant uptake. However as the rhizosphere is the 1 mm area surrounding the root it is directly under the chemical influence of the plant (Pilon-Smits 2005). The difficulty in assigning the extent to which removal is due to microbes or plants is further complicated by the complex relationships that occur in the root zone. Olsen, Reardon & Pilon-Smits, (2003) highlight this when proposing that specific compounds exuded from plant roots may promote growth of microbial communities that can remediate and remove pollutants.

Microbial-nutrient cycles such as nitrogen denitrification/nitrification are also reliant on other biotic factors such as temperature, which further complicates the process. Picard (2005) reports that the optimum temperature for microbial nutrient removal is approximately 30˚C. Werker (2002) agrees with this, reporting that extreme temperatures inhibit the growth of nitrogen reducing bacteria and that nitrification (ammonium oxidized to nitrate) rates are inhibited at 10˚C. Removal of phosphorus is mainly dependent on sediment adsorption (Picard et al. 2005) (see section I.1(c)) and as such is less affected by temperature variation and specific microbial and plant species.

An example of nutrient removal due to microbes is denitrification of nitrate. This process is dependent on the presence of dentrifying bacteria as well as the biotic conditions of the soil (temperature, absence of oxygen and carbon substrates). Angier (2002) states that ground water is commonly denitrified in wetland systems due to anaerobic conditions and high carbon levels. This example highlights the complex interactions between abiotic and biotic factors in an ecosystem, and hence why there is so much variability in the literature.

(b) Plant removal Plant uptake of nitrogen and phosphorus is a biological process that is dependent on transporter proteins. Charged nutrient ions can not pass through charged membranes and as such require a transporter protein (Pilon-Smits 2005). Much of the literature on plant nutrient removal focuses on nitrogen and phosphorus and as mentioned above has produced a lot of variability in rates and measurements of removal. Plant absorption of these nutrients is determined by the plant’s nutrient requirement and is regulated through the transporter proteins (Olsen et al. 2003). It is 6 possible therefore, that this variability comes from the fact that plants stop absorbing these nutrients when the transporter proteins are saturated, whilst removal from proliferating microbes may still continue. De Souza et al. (1999) also highlights another possible cause of variability, that of microbial–plant interactions. Enhanced plant uptake of nutrients may be caused by stimulation of root growth and production of metabolites that affect gene expression of transporter proteins.

Plant requirements explain the uptake of essential nutrients such as nitrogen and phosphorus, however transporter proteins are able to transport other nutrients that are chemically similar to those they are designed for (Pilon-Smits 2005), as such non-essential nutrients can be absorbed by plants. For example arsenate can be transported across plant membranes by phosphate transporter proteins.

Many studies have highlighted the differing effect of plant species, microbial communities and hydrology on nutrient removal. Importantly these studies also recognize the role of many interactions and emphasise the need for further study (Angier et al. 2002; Coveney et al. 2002; Hunter et al. 2001; Picard et al. 2005).

(c) Phosphorus Retention As discussed above, removal of phosphorus has been shown to be mainly dependent on adsorption and sedimentation. Although the specific plant and microbial species of a wetland may not be significant in phosphorus removal, the hydrology, pH, redox state and soil characteristics are. Phosphorus in water exists as both dissolved phosphorus species and particulate phosphorus compounds in a complex equilibrium system with both forms - interchangeable (Wang and Mitsch 2000). Orthophosphate (H2PO4 ) is the main source of bioavailable dissolved phosphorus in the water column. Australian rivers typically contain 95% particulate phosphorus bound to sediments (Webster et al. 2001). Phosphorus retention in sediments can be as a result of adsorption to soil particles, or precipitation with active metal species.

It is generally accepted in the literature that adsorption occurs when the orthophosphate ion is exchanged with the hydroxide ion (OH-) on aluminum and iron hydroxides (Morgan 1997; Nash 7 and Halliwell 2000). As the adsorption of phosphorus is dependent on the presence of these metal hydroxides rates vary with soil characteristics. Retention rates of phosphorus therefore increase with clay content and decrease with increasing sand content.

Furthermore, the pH of the sediment layer heavily influences phosphorus retention rates through the chemical processes of precipitation and availability. Under alkaline conditions adsorption of dissolved phosphorus to calcite (calcium carbonate) is possible. In this case the orthophosphate - - ion (H2PO4 ) replaces the water, bicarbonate (HCO3 ) or hydroxide ions adsorbed to the calcite particles (Morgan 1997). In addition it is widely reported that under alkaline conditions the presence of this active or available calcium causes the precipitation of di-calcuim phosphate. Under acidic conditions (pH<5) the presence of active manganese, aluminum or iron causes the precipitation of hydroxy metal phosphates (Morgan 1997). Consequently, the bioavailability of phosphorus in the water column can be reduced at certain pH levels. Figure 1 and table 1 both show the availability and fixation of phosphorus at various pH levels.

Table 1: Soil and sediment characteristics and their effect on phosphorus retention. Characteristic Retention/Desorption Process Source

pH 4-7.5 Retention Adsorption to Fe and Al hydroxides Gibson (1997)

pH < 5 Retention Precipitation of hydroxy metal phosphate Morgan (1997)

pH > 8 Retention Precipitation of di-calcium phosphate Morgan (1997)

Minimum retention Between the range of Al/Fe and Ca pH 6-6.5 Gibson (1997) Maximum availability fixation

Iron desorbed from clay, release of Webster, Ford & Anoxic (reducing) Desorption phosphate to water column Hancock (2001)

Bridgham et al. Oxic (oxidizing) Retention Solubility of Fe and Al reduced (2001)

8

Figure 1: The effect of pH of on the availability and fixation of phosphorus to soil particles.

As phosphorus is adsorbed to particular species in the soil it stands to reason that the soil can only retain a finite amount of phosphorus. As this capacity is approached and phosphorus inputs continue, the soil or wetland water levels of phosphorus will logically increase. Similarly, if this limit is not reached, inputs to the water column will result in an increase in phosphorus adsorbed by sediments. This agrees with Fisher and Reddy’s (2001) study that found nutrient loading increased total and soluble nutrient levels. Webster et al. (2001) refers to this process as the “phosphate buffer mechanism”.

Webster et al. (2001) illustrates clearly the buffering mechanism of waterways in their study “Phosphorus dynamics in Australian lowland rivers”. Figure 2 (a) below shows the equilibrium that exists between the water column and sediments under constant conditions. Figure 2 (b) shows how the equilibrium responds to removal of phosphorus from the water column. The flux of phosphorus is now one sided towards the water column, and will return to that shown in figure 2 (a) once a new equilibrium is reached.

9

(a) (b)

Figure 2: Phosphorus adsorption/desorption dynamics between water column and sediments when system is (a) at equilibrium and (b) when phosphorus is removed from the water column. Source: Webster et al. (2001)

Webster et al. (2001) also report that the buffering capacity is dependent on the type of sediments as adsorption is determined by the presence of aluminium, iron or calcium in conjunction with clay particles. It follows then that wetlands based on clay soils should have a higher buffering capacity (that is a greater capacity to retain phosphorus in sediments rather than dissolved in the water column) than those based on sandy soils, as they have a higher proportion of these metal species. Such wetlands should therefore, under constant conditions, be less affected by phosphorus inputs. However studies have found that organic matter types and abundance can also affect the equilibrium flux (Bridgham et al. 2001; Fisher and Reddy 2001).

(2) Pesticide removal

The only way to remove xenobiotic organic compounds from the environment is through mineralization (complete degradation) to carbon dioxide, water and inorganic compounds, although partial degradation or adsorption may decrease the measurable concentration (Larsen et al. 2001). Pesticides may be degraded by either plants or microbes, whilst sorption to sediments and organic matter can result in stabilization of the pesticide.

(a) Microbial degradation The degradation processes that occur in the rhizosphere are not fully understood, although the general consensus in the literature is that plants release carbon compounds that encourage growth of specific microbial communities. Secondary compounds are then released that may induce

10 genes in the microbes that are involved in degradation, or are a co-metabolite that allows degradation. Studies such as those by Larsen et al. (2001) and Anderson et al. (2002) highlight the variability associated with measuring the microbial degradation of pesticides.

(b) Plant degradation Pesticides move into plants species by simple diffusion. The hydrophobicity of the pesticide determines if the pesticide can move through the lipid bi-layer of plant membranes (Pilon-Smits 2005). Once the pesticide is in the plant root or shoot it can be degraded by plant enzymes. This can be a complete degradation, or a stable intermediate can be produced which is stored within the plant. Atrazine, a common pesticide, is an interesting example. Pilon-Smits (2005) reports that it is partially degraded by plant enzymes and then sequestered. Anderson et al. (2002) and Larsen et al. (2001), however report that microbial mineralization and sorption to sediments is more prevalent. This again highlights the complex interactions and the associated difficulty in assigning removal to a particular process.

(c) Adsorption As with phosphorus, pesticides can be adsorbed to soil particles or sediments (Brady and Riding, 1996). The pesticide is not degraded in this process but is removed from the water column (Larsen et al. 2001) and prevented from moving downstream. The adsorption of pesticides from water to soil particles is largely dependent on the amount of organic matter in the soil and the solubility of the pesticide (Honeycutt and Schabacker 1994). The equilibrium partition coefficient

Kd relates to the partitioning of a pesticide between soil and water. A high Kd corresponds to a large proportion of the pesticide being associated with the soil phase rather than the aqueous phase. The relationship between Kd and the fraction of organic carbon in the soil can be used to determine the partitioning between organic matter and water, given by the partition coefficient

Koc. Barbash and Resek (1996) state that Koc values for a pesticide can be used across a broad range of soils due to the non specific nature of organic matter. Although pesticides can be characterized by their solubility and partitioning coefficients, the retention due to adsorption in wetland systems can vary dramatically. As discussed above, atrazine has been shown to be adsorbed by wetland sediments (Anderson et al. 2002; Larsen et al. 2001). However studies by Angier et al. (2002) and Kao et al. (2001) found that atrazine was not adsorbed by sediments in the study wetlands, despite high levels of organic matter. These variations could be as a result of

11 different flow regime and retention times. Because the retention of a pesticide depends on the physical properties of the chemical and the wetland, it is important that the retention capacity be determined on a case by case basis.

12 III. The Macquarie Marshes

The Macquarie Marshes are a non terminal, alluvial fan wetland system located in the lower third of the Macquarie valley that flow into the Barwon-Darling river system north-west of Carinda (Kingsford 2000; Kingsford and Auld 2005). Figure 2 shows the location of the Macquarie Marshes and Burrendong Dam.

Figure 3: Location of the Macquarie Marshes in relation to Sydney, local towns and Burrendong Dam. Source: Fazey (2006).

The average slope of the Marshes is 50 cm per 100 m, whilst the average annual rainfall is 414 mm (although water does flow from areas with higher rainfall) (Brock 1998). The Marshes are located in the summer dominant rainfall area, and have a temperature range of 4-44 degrees Celsius (Kingsford and Thomas 1995). Brock (1998) reports that the western side of the marshes are dominated by red-brown dermosols, while the eastern side is dominated by clay based grey- brown soils.

13 Burrendong Dam located near Wellington (figure 2) is the main water diversion that controls water flow to the Macquarie marshes. The dam is responsible for regulating 70% of flows from the Macquarie catchment (DLWC 1996)

The Macquarie Marshes planning area covers 201 330ha, 10% of which is nature reserve – this is split into two areas, the north and south nature reserves (Brock 1998). These areas are run by the national parks and wildlife service and are recognized as wetlands of environmental importance under the RAMSAR convention and under international agreements such as the Japan/China and Australian migratory bird agreement (JAMBA/CAMBA) (Herron et al. 2002; Kingsford 2000). The remaining 90% of the planning area is freehold land that is mostly used for agriculture. Cattle are grazed in the wettest areas while broad acre crops are grown on the drier surrounding land. Irrigated cotton is now the major broad acre crop grown in the Macquarie valley having tripled between 1985 and 1995 (Herron et al. 2002)

(1) Biodiversity of the Macquarie Marshes

The Macquarie Marshes provide habitat for many bird species, including more then 60 species of water birds, 42 of which breed in the area (Kingsford and Thomas 1995). The area also supports a diverse array of native flora and fauna (Brock 1997). The marshes have the largest reed beds, largest area of red gums and the most southerly occurrence of Coolabahs in N.S.W (Kingsford 2000). Tables 2 and 3 below highlight some of the important species found in the Macquarie Marshes

Table 2: A selection of bird species found within the Macquarie Marshes (E) signifies endangered species Common name Scientific name Source Glossy Ibis Plegadis falcinellus Webb & Fissher (2001) Australian White Ibis Threskiornis mollucca Kingsford (1994) Straw Necked Ibis Threskiornis spinicollis Johnson (1992) Intermediate Egret Egretta intermedia Kingsford & Thomas (1995) Rufous Night Herron Nyclorax caledonicus Brock (1998) Bush Thick Knee (E) Burhinus magnirostris Riverine Environment Unit (2000) Square tailed Kite (E) Lophoictinia isura Webb & Fisher (2001)

14 Table 3: A selection of plant species found within the Macquarie Marshes Common name Scientific name Source Common Reed Phragmites australis Riverine Environment Unit (2000) Cumbungi Typha orientalis Herron et al. (2002) Water Couch Paspalum paspalodes Brock (1997) Flood Plain Eucalypt Eucalyptus camaldulensis Lemly et al. (2000) Flood Plain Eucalypt E. microtheca Paijmans (1981) Flood Plain Eucalypt E.largiflorens Brock (1998)

(2) Regulation of flows to the Macquarie Marshes

Burrendong dam at Wellington regulates the flow of the Macquarie River in order to allow irrigation and as a flood mitigation tool. The dam was constructed in 1967 and has a storage capacity of 1, 678 000 ML1. The history of Burrendong dam and the allocation of water to the Macquarie Marshes is shown in table 4.

Table 4: The compiled history of Burrendong Dam and wildlife water allocations to the Macquarie Marshes Year Action Source 1967: - Construction of Burrendong dam Brock (1998) - 50 000 ML determined to be the amount necessary to initiate and Kingsford & Thomas support bird breeding (1995) - 18 500 ML of water was delivered to the marshes

1970: - 18 km bypass channel built, which diverts water around the DLWC (1997) northern nature reserve.

1979 - Embargo on new licenses Brock (1998)

1986: - Wildlife allocation of 50 000 ML was implemented under the DLWC (1997) management plan Found to be inadequate due to increased irrigation 1994 - Review of the 1986 Management plan Davis et al. (2001)

1 1ML = 1 million litres 15 - Call for full cost recovery in water pricing

1996: - New management plan released Davis et al. (2000) - Increase to 125 000 ML of wildlife allocation, to be released at Kingsford (2000) rainfall events Brock (1997) - Access to off allocation water was reduced. A cap of 50 000 ML per year imposed. - Total diversions for irrigation were decreased from 395 000 ML per year to 340 000 ML - NSW government implemented an interim water management charge: irrigators and towns located on regulated rivers were charged $1.35 per ML, this was in response to the 1994 call for full cost recovery in water pricing

2000 - Water management act introduced – required negotiation of Smiles (2006) water sharing plans (WSP) - Compensates license holders if more water is returned to the environment then stated in the WSP - Wildlife allocation increased to 160 000 ML (general security)

Although the flood mitigation role of the dam from a community cost and safety viewpoint is important, flood mitigation is seen by many to be negatively affecting ecosystem health downstream due to reduced flow variability (Brock 1998; Kingsford 2000; Wittington and Hillman unknown date).

IV. Agriculture in the Macquarie Valley

16 (1) Irrigated cotton production

The N.S.W. Irrigators Council (2001) reported that irrigated agricultural production in the Macquarie Valley was worth $247.6 million per anum. Agriculture uses 89% of the water extracted from the Macquarie Valley (Fazey et al. 2006), of which 60% is used for cotton production and produces the majority of the revenue (Herron et al. 2002). Dryland wheat production was the dominant broad acre crop until irrigation commenced after the construction of Burrendong dam in 1967 (Kingsford 2000).

All water from regulated systems is subject to allocation by volume; licenses specify a volume of water and all extractions are metered. Water storage (the amount in Burrendong dam) is assessed at the start of each water year to determine the amount of water available, and is then divided between all general allocation holders. Producers that hold a general allocation license do not necessarily receive 100% of their allocation, as they are calculated on 100% storage. However “off allocation” water may be used to compensate for this later in the season. Off-allocation may be declared when “supply in any section of the (Macquarie) river exceeds orders as a result of tributary inflow, storage spills or unused releases” (DLWC 1997). This water is not debited against the irrigators’ volumetric water allocation. The use of off-allocation water was not controlled until 1996, when a cap of 50 000 ML was introduced (Brock 1996).

Regulation allows irrigators to plan with a high degree of certainty, as they know at the start of the water year what their allocation will be. Because of the conservative approach taken it is unlikely that this allocation will be reduced during the water year (DLWC 1996). On the other hand, water users and environmental groups further down the system often feel that their water has been stolen by irrigators upstream (Brock 1996).

The increase in irrigated agriculture in the Macquarie valley, especially downstream of Burrendong dam has caused a reduction in the amount of water reaching the Macquarie marshes. Nevertheless Brock (1998) states that under the 1996 management plan the Macquarie Marshes are receiving 85% of natural flows. This has not changed under the 2004 Macquarie –Cudgegong water sharing plan, however the water can be delivered in a more variable manner then previously.

17 In addition to decreased flows, cotton production has also received criticism in the past over pollution of waterways with pesticides. However, this has been somewhat addressed through the introduction of ‘best management practices’ guidelines.

(2) Cattle production

Cattle production has a long history in the Macquarie valley, especially within the marsh planning area. As stated above, 90% of this area is freehold land that surrounds the nature reserves. The number of cattle grazed in the area has decreased since the introduction of more profitable irrigated crops, however the area is still socially and economically dependent on cattle production (Brock 1996). Grazing is prevented in the nature reserves; however there are no buffer zones as exist with cotton production. This means that areas that cannot legally be used for cotton production can be grazed. These areas are often highly productive and provide high quality feed for cattle (Mathias and Moyle 1992). Producers that border with the nature reserve are able to graze cattle up to the border of these areas (Brock 1997).

Despite the long history of grazing there are environmental issues associated with grazing marsh land. The main criticisms leveled at graziers are the decrease in water quality due to erosion and nutrient loading and the damage caused to reed beds (Brock 1996). Accusations have also been made about the diversion of water through the use of illegal levy banks to flood pastures for grazing (Meadows 2006). This essentially means that such graziers are illegally and directly benefiting from environmental allocations, while marsh areas downstream are not receiving the intended amount.

Kingsford and Thomas (1995) state that the wetland area has decreased by 40-50% since the construction of Burrendong Dam, whilst cattle production has been shown to affect water quality (Riverine Environment Unit 2000). The introduction of agriculture has altered the Macquarie Marshes and as such it is important to monitor the health of the marshes in relation to agriculture.

V. Competition for Water Resources

18 The Macquarie River supplies water for townships, agriculture and the environment. It is no surprise then that there is tension associated with who receives how much of the water. As discussed in section II, the main industry in the Macquarie valley is agriculture. Agriculture is interdependent on small business suppliers such as contractors, mechanics, machinery dealers, grocery stores, and petrol stations. Thus the provision of water to irrigated cotton production (the main source of revenue in the area) and cattle production (a historically and socially important industry) is particularly important. However, water must also be supplied to townships for drinking, cleaning and other household uses. The different stake holders and the overlapping demands are shown in figure 4. Environment Cattle Production Cotton production

community Figure 4: Representation of the stakeholders and the overlapping demands for water.

Finlayson & Mitchell (1999 p 109) state that “in the past the needs of the individual agricultural water users has received more recognition from managers then have the needs of the Marshes”. Increasingly the problems with this type of management are coming to the fore. It is being realised that water must also be returned to the environment to enable the continuation of ecosystems and the survival of important flora and fauna. This increased awareness of the environment has lead to a push for sustainable agriculture that causes as little damage to the environment as possible. This has put a lot of pressure on both the irrigated cotton and cattle production industries in the Macquarie valley. Brock (1996) explores the irrigators and graziers perceptions of management issues and highlights the fact that both industries are concerned and frustrated with the criticisms about their industries. Yet despite this there is political tension between the two industries. It is important to consider the politics behind the environmental issues, as it gives the context of the problems, and also because the environmental issues are

19 becoming more and more socially relevant. The divisions of this area are often used to illustrate the destructive nature of agriculture and the inability to adequately manage the water resources of the country.

The major dispute between the two industries is based on the availability and allocation of water and how this affects the production potential of both industries (Brock 1996). Graziers often comment that the extraction of water upstream by cotton producers has left the marshes vulnerable and has decreased their ability to make money (Fazey et al. 2006, Jones pers. comm.). Brock (1996) reports that the main concern by graziers is that their water has been stolen by irrigators. Fazey et al.(2006) reports that managers of the Marshes felt that the “extensive lobbying power” of the irrigation industry will more than likely result in policy and management that will favour the irrigation industry. These accusations have damaged the reputation of the cotton industry. The cotton industry in turn has commented that grazing has lead to loss of biodiversity and decreased water quality, which affects the marshes more than reduced flows (Hogendyk pers. comm.). These perceived problems and management views are shown in table 5.

There has also been recent backlash against the building of illegal banks and channels that divert environmental flows onto grazing areas (Meadows 2006). The article these accusations appeared in directly calls into question the management by government departments: “contacts within the department have told the Inland Rivers Network that no action is likely to be taken against the thieves”. Interestingly this article also indirectly brings into question the assertion that graziers are only interested in protecting the marshes from irrigators, as directly stated or implied in various studies and reports.

Meanwhile, as the accusations and criticisms continue, management of the system proceeds in the same manner. Major papers such as the Sydney Morning Herald have recently printed articles on the politics and health of the marshes that raise the question: is the environment more important then continual dispute? (SMH 2006). The wider public is being shown a fragmented, frustrated community on the verge of collapse. However the effectiveness of these emotive pieces (Table 6) must be questioned – are they rallying the public behind the environment in general or one particular stakeholder group? This is a complex social, environmental and economic issue that will not be solved with a one pronged approach.

20 The politics is important; however the health of the ecosystem and the future of agriculture should remain the key issues. As such it is important to try to identify the cause(s) of the degradation of the marshes, and use adaptive management strategies to deal with this, while ensuring the economic future of the area. In order to achieve this it is vitally important to have valid scientific information on these issues.

21 Table 5: Summary of stakeholders views on problems and solutions regarding the Macquarie Marshes

Stakeholder Perceived Problem Perceived Effect Proposed Solution Source Group Graziers To much extraction Loss of Biodiversity No access to “off allocation” water Brock (1996) Lessened potential cattle production Reduced Regulation of large and medium floods Jones pers. comm. Cotton growers Grazing in marshes Erosion Stop grazing in marsh areas, Brock (1996) Channel formation especially on reed beds Decrease in water quality Limit direct access to waterways Hogendyke pers. comm. Managers a. To much extraction a. Loss of Biodiversity a. - place an embargo on extracting Fazey et Lessened potential cattle production water that enters the river below Burrendong dam. al.(2006) - Purchase water licenses to increase effective wildlife allocation. - Greater enforcement of licenses

b. water supply to suit b. Decreased bird breeding and b. Base time and rate of releases on irrigators, not flooding, increased erosion natural system. environment

c. difficulty c. lack of confidence in the willingness c. Major government intervention communicating with of water agencies to provide for the water agencies environment.

22 Table 6: Examples of articles printed in the public domain that discuss the state of the Macquarie Marshes and views on the management and politics of water resources.

Macquarie Marshes: An icon for - “The current conditions of the Macquarie Marshes is a symbol of the failure of the NSW water reform wetland survival in Australia process” (Smiles 2006) - “The federal and state governments’ commitments under international agreements to protect these wetlands are not being met”

Water burglars target the - “Water thieves are coming up with more cunning ways to steal water earmarked for the environment” Macquarie Marshes (Meadows 2006) - “The government must clamp down on illegal water harvesting, otherwise taxpayers money and our priceless rivers and wetlands will go down the drain”

On the banks of disaster - “As the flow slows, mistakes in water management are left exposed” (Woodford 2007) - Mark Etheridge - “Any new management system can’t be worse than allocating water in a no flow situation”

‘Fat ducks mean fat cattle’ – fat - “On one side of the river stand the irrigators, on the other the graziers, both are pointing the finger over chance the demise of the Macquarie Marshes.” (SMH 2006) - “Its not just about fat cows and fat ducks it’s about people and towns and employment.”

- “What about the shops that are closed, people that have left town, houses that won’t sell.”

23 VI. Degradation issues

(1) Nutrient levels

Nutrient loading of fresh water resources is an environmental concern across Australia and the world. As mentioned in section I.(1) high nutrient levels can lead to toxic algal blooms and degradation of water quality. Eutrophication of waterways can affect native flora and fauna, livestock, irrigation and town water supplies. The Macquarie Valley has many industries and ecosystems that are dependent on the water from the Macquarie River hence it is vital to keep the quality of this water as high as possible.

The Department of Natural Resources has been monitoring the water quality of the central northwest of N.S.W. for many years. This has included pesticide and nutrient analysis of the major basins within the area. In the 1993/94 study a site directly downstream of the Macquarie Marshes was introduced (the study had previously focused on sites up stream of the Marshes). This site was introduced to “provide information on the effect of the Marshes on nutrient loads entering the Barwon – Darling” (D.N.R. 1994). As has already been discussed theory suggests that the Marshes should act as a filter and remove nutrients and pesticides from the water. The results of these studies however show that the concentration of total phosphorus in stream water was usually higher at the Carinda site at the end of the marshes, then entering at Oxley (see figure 5 below). The annual median total nitrogen value was also regularly higher at Carinda then at Oxley2.

2 Monthly sampling data was not available for total nitrogen concentrations

Figure 5: Total phosphorus concentration at three sites along the Macquarie marshes, Oxley station, upstream of the Marshes, Bulgeraga ck, south-east of the marshes and Carinda, downstream of the Marshes (D.N.R. 1994).

The site has been kept in the monitoring program and reports show that the general trend has continued. The median nitrogen and phosphorus values3 for most years from 1993- 2000 are shown in figures 6 and 7. Prior to 2000 ANZECC (1992) stated that it was not appropriate to set a single concentration limit which would prevent excessive plant growth, however a range of concentrations at which algal growth was known to occur was given as an indicator of water quality. In 2000 a local trigger system was introduced, for nitrogen and phosphorus in a specific area, a value is given that is a trigger for ecosystem protection (ANZECC 2000). The upper concentration from the 1992 system and the local trigger value are both shown in figures 6 and 7.

It is unfortunate that routine monthly sampling data is not available for each of the years, to allow for seasonal trends to be assessed.

3 Values compiled from relevant ‘Central and north west Regions Water Quality Program’ reports produced by the Department of Natural Resources. 25 Total Phosphorus Concentration in the Water Column Before and After the Macquarie Marshes

140

120

100

Oxley 80 Carinda ANZECC 1992 Upper Limit

60 ANZECC 2000 Trigger Value

Total phosphorus (ug/L) 40

20

0 93/94 94/95 95/96 97/98 98/99 99/00 Year

Figure 6: Total Phosphorus concentration in the water column upstream (Oxley) and downstream (Carinda) of the Macquarie Marshes. Also shown is the ANZECC upper limit (100ug/L), at which excessive algal growth is known to occur and the ANZECC local trigger value

Total Nitrogen Concentration in the Water Column Before and After the Macquarie Marshes

1600

1400

1200

1000 Oxley

Carinda 800 ANZECC 1992 Upper Limit 600 ANZECC 2000

concentration (ug/L) Trigger Value

400

200

0 93/94 94/95 95/96 97/98 98/99 99/00 Year Figure 7: Total Nitrogen concentration in the water column upstream (Oxley) and downstream (Carinda) of the Macquarie Marshes. Also shown: ANZECC upper limit (750ug/L) at which excessive algal growth is known to occur & the ANZECC local trigger value (600ug/L)

26 Figure 3 shows that all of the annual median values for both sites, except one in 1997, exceed the trigger value for phosphorus of 50ug/L. Figure 4 shows that the majority of annual median values also exceed the trigger value for total nitrogen.

Also important when considering the potential for algal blooms is the total nitrogen to total phosphorus ratio (TN:TP). A ratio of less then 29:1 is conducive to algal growth according to the Blue-Green Algae Task Force (1992). Although as the ratio across the central northwest normally ranges from 2 to 10, the DNR (1993) suggests that factors such as water clarity, temperature and velocities are more likely to determine if algal blooms occur and as such TN:TP is generally not used as an indicator. The ANZECC guidelines also recognize that there are problems associated with using the TN:TP method (ANZECC 2000).

The generation of nutrients within the marshes was offered as a possible explanation for the increase in concentration, as was evapo-concentration. This section aims to investigate the agricultural activities in the area that could potentially generate additional phosphorus and nitrogen to that entering the marshes.

(a) Potential source of Nutrients: Grazing Nash & Halliwell (2000) state that erosion and dissolution are the two main processes of phosphorus mobilization from soil to water ways. Erosion is defined as the ‘transport of sediment (material that does not fit through a 0.45um filter) and the adsorbed phosphorus’, whereas dissolution is ‘the transport of dissolved phosphorus or that attached to material that will pass through a 0.45um filter’. Within waterways, phosphorus movement is controlled by adsorption/desorption processes (see section I.1(c) and figure 1). Wang & Mitsch (2000) propose that deep sediments are a ‘dead end” storage area for nutrients in wetlands where no decomposition occurs. The phosphorus is stored in these sediments unless they are exposed to the water column. This is then referred to as the active sediment layer, and is where the majority of adsorption and desorption occurs.

27 Coveney et al. (2002), Chambers et al. (1993), and Finlayson et al. (1986) all conducted experiments or studies that found wetlands were able to remove phosphorus from input water. These studies also all concluded that disturbance to the wetland caused a net release of phosphorus. Coveney et al. (2002) found that disturbance to the wetland caused chanelisation of flow which increased total suspended solids several fold and decreased sedimentation rates. Finlayson et al.(1986) found that a minor disturbance resulted in a net release of phosphorus and also a decline in nitrogen retention. Importantly the wetlands were reported to return to the levels of retention experienced prior to the disturbance. This appears to concur with Wang’s theory of active and deep sediment layers and the phosphate buffer equilibrium discussed by Webster et al. (2001).

These studies suggest that grazing by large cloven hoofed animals such as cattle can cause the deep sediment layer to be disturbed. The shallow nature of the Macquarie Marshes means that cattle are able to graze directly in the channels of the marsh areas and therefore re-suspend this deep sediment storage layer. Continual disturbance of an area will mean that the suspended particles are not able to settle out and may disrupt the phosphate buffer equilibrium. However it is not clear from the literature how this would affect downstream phosphorus levels.

In addition to re-suspending sediments, grazing in reed beds has also led to channelisation, which increases erosion. Channels are caused by cattle following the path of least resistance as they graze. This leads to preferential flow, as water will also follow this path. The lateral flow across the reed bank is therefore decreased whilst the flow down that channel increases. Increased flow through non vegetated channels in turn leads to further erosion. This, as described by Wang & Mitsch (2000), is one of the major sources of phosphorus transfer and is also an important transport pathway for nitrogen. Nitrogen that degrades water quality is transported in soil organic matter or as nitrate

(NO3), although ammonium (NH4) is also transported attached to sediments (Follett and

Delgado 2002). Selective detachment of fine sediments containing NH4 and nitrate leads to a high concentration of total nitrogen in waterways (Delgado 2002).

Erosion is also a concern in the area between the southern and northern nature reserves. In this area there is surface and stream bank erosion due to lack of vegetation and direct 28 access to stream banks. Erosion of this soil into waterways can also lead to desorption of orthophosphate into the waterways (Wang and Mitsch 2000). Erosion of top soil due to overgrazing and clearing of ground cover can have a large impact as the surface layer of the soil is highest in orthophosphate, due to the rapid fixation rates. Nitrogen loss from this area is also likely to be significant if nitrogen fertilizers are applied to improve pasture productivity.

In grazing systems phosphorus and nitrogen are mainly returned to the soil in animal faeces. Nash & Halliwell et al. (2000). state that the organic phosphorus component remains the same as that taken in by the animal. Grainger at el. (1985) found that the daily faeces (3kg) of lactating dairy cows contained 0.015-0.3 kg of phosphorus. Similarly most nitrogen consumed by livestock is returned to the system. Follet & Delgado (2002) report that a steer that ingests 180g of nitrogen will excrete 160g, 74% of which will be excreted in urine. As such, direct grazing in waterways could cause an increase in the phosphorus and nitrogen content of the waterways. It is difficult though to know if this would be obvious in a site many kilometers downstream.

(b) Potential source of Nutrients: Change of flow patterns Reduced flow variability leading to continual low flows has been cited as a cause of stream bank erosion up stream of and within, the Macquarie Marshes (D.N.R. 1994; Morrison et al. 1999; Riverine Environment Unit 2000). Transects of the cross sectional area of various creeks in the southern Marsh system from the 1960’s, 1992 and 1995 show that significant erosion and enlargement (width and depth) of these waterways has occurred (Riverine Environment Unit 2000). The authors of the study state that although a combination of factors is likely to be responsible for this erosion, the change to continual low flows, due to regulation of the system, is the dominant factor. This quantitative material gives emphasis to the claims of Brock (1998), Whittington and Hillman (2000), and Kingsford (2000), all of whom have stated that continuous low flows have caused bank erosion and increasing width of waterways in the Macquarie Marshes. As discussed earlier erosion is a possible and probable transfer pathway for phosphorus and nitrogen.

29 The construction of the northern bypass channel in the late 1960s is also reported to have an affect on the nutrient levels exiting the marshes. Flows from the Southern Marshes are diverted through the bypass channel when flows are less then 100 ML per day (Bennett and Morrison 2000; D.N.R. 1994). Flows of several hundred megalitres per day and the closure of the bypass channel allow the water to travel through the Northern Marshes, a much more vegetated and stable area. As such, stream bank erosion in the bypass channel is avoided and passage through the marshes means there is an increased likelihood that dissolved nutrients will be removed from the water column.

Erosion in the Southern Marshes is particularly important especially in times of low flow. The advantageous passage of this nutrient and sediment enriched water through the Northern Marshes does not occur. Instead the water continues through the by-pass channel, which is poorly vegetated and an erosion risk in itself. The dominance of this water at low flow periods may partially explain the high nutrient levels, as sampling does not occur at the edge of the Northern Marshes, but downstream at Carinda. Quinton et al. (2001) found that frequent low magnitude erosion events contributed the majority of phosphorus transferred from soil to water over a six year period. This highlights the potential effect of continual stream bank erosion on nutrient levels in the water column exiting the Northern Marshes.

An uninterrupted section of nature reserve downstream of both the end of the bypass channel and the northern nature reserve may help to decrease the nutrient concentration of the water at Carinda when water is diverted through the bypass channel. An additional section of marsh has the potential to cause the sedimentation of excess particulate nutrients and increase the removal of dissolved nutrients from the water column that have resulted from upstream erosion. While this does not address the cause of the problem it has the potential to be one part of an integrated solution.

(2) Regulation

The frequency of large (250 000 ML – over 400 000 ML) and medium (150 000 ML - 250 000 ML) floods in the Marshes have decreased by 50% and 25% respectively, due to the regulation by Burrendong Dam (Brereton et al. 1996 - Cited in Brock (1998) pg 79). 30 This in combination with stream bank erosion means that over-bank flow occurs less frequently as the amount of water required increases. Kingsford and Thomas (1995) report that this has lead to the reduction of the area of the Macquarie Marshes by 50%. The Riverine Environment Unit (2000) reports that the number of breeding water bird species increases with the volume of flooding. This is in agreement with Kingsford and Thomas (1995), Kingsford (2000) and Kingsford and Auld (2005) who attributed decreased colony sizes and frequency of water bird breeding to reduced flood volumes and frequency.

Brock (1998) states that change to vegetation has been mainly caused by changes in flood regimes. This is in agreement with Kingsford (2000) who reports a decrease of 14% of River Red Gums, and the death of many hundreds of hectares of coolibahs. Interestingly the Red gums were apparently killed because of a lack of water and the retention of water behind levee banks is reported to have killed the Coolibahs. This highlights the complex biodiversity of species that is present in the area and the consequences significant changes can have.

Adaptive management techniques have been suggested as a potential solution for the problems associated with river regulation (Fazey et al. 2006). Adaptive management attempts to increase the variability with which environmental water is delivered. This aims to achieve a more natural flow pattern with a higher percentage of large flood events. This would appear to be a partial solution to erosion as larger flood events will then pass through the northern nature reserve and in addition facilitate water bird breeding. Because of the large number of stakeholders, the implementation of such a program would require planning and approval to ensure no one was unnecessarily disadvantaged, but would be a significant step in the right direction.

(3) Pesticide contamination

Pesticides can have adverse affects on flora and fauna. The Macquarie Marshes are a stressed area that is habitat for many species of birds, animals and plants. As discussed earlier this is important in terms of biodiversity and species continuation. The effect of

31 pesticide contamination could range from the death of one or two individuals to destruction of a community, depending on the type and concentration of the contaminant.

Pesticides are regularly used in both irrigated and dry land cropping production. Cotton is the main crop in the vicinity of the Macquarie Marshes and as such has the highest potential to contaminate water ways. Although there is a buffer area around the nature reserves within which cotton is prohibited, pesticides can potentially enter waterways through storm run-off and aerial spray drift and affect the flora and fauna of the Marshes. Muschal and Warne (2003) found that for the in-land rivers of northwest N.S.W chlorpyrifos, endosulfan and profenofos posed an acute risk to aquatic organisms during the spraying season. Brock (1998) reports that endosulfan was detected in the Northern Marsh prior to 1995. The DNR reports that endosulfan was detected above the ecosystem protection limit, but well below the limit for human consumption from 1991-1998.

The best management practice guidelines cover the timing and method of application of pesticides and also state that all tail water (used irrigation water) must be recycled on farm. This means that the tail water is retained on the farm, along with any pesticide it contains. Macathur Agribusiness (2004) reports that the introduction of best management practices has resulted in improvement in water quality and reduction in spray drift and fish kills. Despite this it is still important to continually monitor the waterways for the presence of pesticides.

32 VII. Conclusions This review examined the scientific literature and data on wetland function and the factors affecting the Macquarie Marshes. The literature suggests that wetlands generally have the capacity to remove and retain sediments from the water column under optimal conditions. However, disturbances can cause a nest release of nutrients. There are many interactions and processes that contribute to the removal and retention of nutrients and pesticides, as such there is a lot of variability in this section of the literature. Additional research needs to be undertaken in arid non-constructed wetlands such as the Macquarie Marshes to facilitate understanding of the effect of human intervention on the optimal function of such a wetland.

A complex mixture of anthropogenic stressors has resulted in the Macquarie Marshes being a highly stressed ecosystem that does not appear to be filtering phosphorus or nitrogen as it is expected to. The potential detrimental effects of excess nutrient levels include toxic algal blooms and decreased water quality. Erosion from grazing of cattle and continual low water flows has been demonstrated as a significant contributor to water column levels of nitrogen and phosphorus. As such, management of erosion should be a high priority.

33 Paper 2: Thesis

WATER QUALITY AND FILTERING CAPACITY OF THE MACQUARIE MARSHES Leah McCarroll, Sciences Discipline, Faculty of Agriculture, Food and Natural Resources, University of Sydney, NSW 2006, Australia

Abstract This study investigated the water quality of the Macquarie Marsh system in order to asses the effect of land use on water quality and the filtering capacity of the Marshes. Nine sites along the length of the marshes, (grazing areas, cotton production & marsh) were sampled in January, February, April and September 2007. The nitrogen, total phosphorus, orthophosphate (available fraction) and herbicide concentrations were analyzed for each site as indicators of water quality and used to calculate the mass balance of the system. All concentrations of Atrazine, Fluometron, Diuron and Metachlor were below the detection limit of 10ppb. The pH and EC of all sites remained stable over the study period. Fourteen percent of the sample averages exceeded the environmental nitrogen trigger value of 500 µg L-1, whilst 83% of the total phosphorus sample averages exceeded the trigger value of 50 µg L-1. Comparatively, only 22% of the orthophosphate averages exceeded the trigger value of 20 µg L-1. Areas of high grazing pressure were shown to have higher than average orthophosphate concentrations in two of the four sampling periods, indicating the addition of available P due to disturbance of sediment and erosion. The site in the interior of the Marshes consistently had the highest concentration of all nutrients due to the high rate of organic matter decomposition.

Load calculations showed the increase in concentration was a result of evapo- concentration and the decrease in volume of water downstream. In January, 16.8 kg of nitrogen and 7.3 kg of total phosphorus were removed between Marebone Weir and Bell’s Bridge. A significant decreasing trend in salt load was also seen between these two sites. Significant reductions occurred over the area of the Northern Marsh (60Kg N in January and 37 Kg in February, and 3.3Kg of TP in January). The marsh system is therefore capable of filtering nutrients even in a low flow year. This study also highlights the importance of using appropriate data to make scientific and environmental recommendations. Both concentration and load data should be considered to maximize the health and functioning of the system. Key Words: Macquarie Marshes, Wetlands, Phosphorus, Nitrogen, Total Load. 34 I. Introduction This study is focused on the water quality of the Macquarie Marshes, particularly in regard to nutrient levels and the effect of land use on water quality and the ecological functioning of the Marshes. The Macquarie Marshes are a non terminal wetland located in the Macquarie valley of northwestern New South Wales (N.S.W.) (Figure 1.)

Figure 1: Location of the Macquarie Marshes, showing the course of the Macquarie River from Dubbo to Carinda. Source: Fazey (2006)

The Macquarie river runs from the south to Burrendong dam where the flow is controlled, onwards to Warren, north of which it begins to diverge into many small and large tributaries. With an average slope of 50 cm per 100 m and meandering, diverging waterways, the area between Warren and Carinda is commonly collectively referred to as the Macquarie Marshes (Brock 1998); In fact, only 10% of this 201,330 ha (known as the Macquarie Marshes planning area) is actually recognized and protected as a wetland of international importance under the RAMSAR convention (see figure 2). The remaining 90% of the planning area is freehold land and is used mainly for cotton production or cattle grazing. The protected 10% is split into the Northern and Southern Nature Reserves which are run by the National Parks and Wildlife Service and are recognized in

35 agreements such as Japan/China and Australian migratory bird agreement (JAMBA/CAMBA). The Macquarie Marshes provide a habitat for many bird species, including more than 60 species of water birds, 42 of which breed in the area (Kingsford and Thomas 1995). The area also supports a diverse array of native flora and fauna (Brock 1997). The marshes are significant, having the largest reed beds, largest area of red gums and the most southerly occurrence of Coolabahs in New South Wales (Kingsford 2000).

In addition to supporting a diverse range of flora and fauna, the area is an important agricultural area, with many broad acre crop and livestock enterprises located within the planning area. Cattle production has a long history in the Macquarie valley, especially within the marsh planning area. The number of cattle grazed in the area has decreased since the introduction of more profitable irrigated crops, however the area is still socially and economically dependent on cattle production (Brock 1996). Grazing is prevented in the nature reserves; however producers who border with the nature reserve are able to graze cattle up to the border of these areas (Brock 1997). These areas are often highly productive and provide high quality feed for cattle (Mathias and Moyle 1992). The areas in which, and the methods by which cotton can be grown, near the nature reserves are regulated to protect ecosystems; although irrigated cotton production is still an increasingly important and valuable enterprise. The N.S.W. Irrigators Council (2001) reported that irrigated agricultural production in the Macquarie Valley was worth $247.6 million per anum. Agriculture uses 89% of the water extracted from the Macquarie Valley (Fazey et al. 2006), of which 60% is used for cotton production, which also produces the majority of the revenue (Herron et al. 2002).

Many authors have reported that anthropogenic stressors including alteration of natural flow patterns, diffuse and point source inputs of nutrients and the loss of marsh vegetation has led to a highly stressed ecosystem. Kingsford and Thomas (1995) state that the wetland area has decreased by 40-50% since the construction of Burrendong Dam. The biodiversity of flora and fauna in the area has also been found to be decreasing (Paijmans 1981).

36 Although scientific literature suggest the Macquarie Marshes should act as a filtering mechanism (Coveney et al., 2002, Finlayson et al., 1999) often the nutrient concentration exiting the marshes exceed that entering the system (DNR, 1993-1999).

The Department of Natural Resources has been monitoring the water quality of the central northwest of N.S.W. for many years. This has included pesticide and nutrient analysis of the major basins within the area. In the 1993/94 study, a site directly downstream of the Macquarie Marshes was introduced (the study had previously focused on sites up stream of the Marshes). This site was introduced to “provide information on the effect of the Marshes on nutrient loads entering the Barwon – Darling” (D.N.R. 1994 pg. 3). The results of these studies show that the concentration of total phosphorus in stream water was generally higher at the Carinda site at the end of the marshes, then entering at Oxley gauge. The annual median total nitrogen value was also regularly higher at Carinda then at Oxley. The site has been kept in the monitoring program and reports show that the general trend has continued. This data indicates that the marsh may not be filtering the water as expected. The reports also show that the annual median values for both sites, except one in 1997, exceed the ANZECC (2000) trigger value of 50 µg L-1 for phosphorus. The majority of annual median values also exceed the trigger value for total nitrogen

The high concentration of phosphorus and nitrogen and the trend to increase through the system, recorded in these studies raises two major concerns. One of which is the potential for eutrophication of the waterways as a result of high nutrient concentrations. Picard (2005) states that eutrophication is the most significant water quality problem throughout the world. Excess nutrients can have many detrimental affects on waterways and surrounding ecosystems, and their removal by wetland areas is considered extremely important. Excess nitrogen and phosphorus can lead to algal blooms (Angier et al. 2002) and the occurrence of waterborne bacteria, such as Pfeisteria piscicida (Buck et al. 1997). Blue green algae, a group of cyanobacteria, can have detrimental effects on ecosystem health and can produce toxins harmful to fauna and humans. As algal blooms senesce, decomposition reduces the dissolved oxygen of the waterways. Reduced levels of dissolved oxygen in the water column have serious effects on the aquatic system and can further degrade water quality (DLWC 1997). 37

The second concern is regarding the elevated nutrient trend after the marsh system. This appears to go against the scientific understanding of wetland systems, and is also being used to substantiate the theory of degradation of the system due to agricultural enterprises. As stated by the DNR, the distance between the sites (approximately 200 km) and the various land uses and ecosystems contained within that area, in addition to the type of data, means that this is should not be used as an indicator of degradation or causes.

This report aims to investigate the reasons for the higher concentration of nutrients downstream of the marshes as well as forming a pilot study of the water quality throughout the system to aid future research. The waterways along the length of the marsh were tested at significant spots (as addressed in the methods section) to give an overview of potential sources of nutrient loading. Of the many streams, creeks and rivers in the area between Warren and Carinda, the three major water ways which travel through the eastern side of the nature reserve were sampled – the Macquarie River, Monkeygah Creek and Bulgeraga Creek. As agriculture is a potential cause of water degradation, sites within cotton and cattle enterprises were sampled, as was water from within a marsh area. The concentration of total phosphorus, total nitrogen and orthophosphate was analyzed as an indicator of water quality, whilst total observed daily load was calculated (where possible) to give insight into the mechanics of the system. The concentrations of Atrazine, Diuron, Metachlor and Floumetron, commonly used herbicides, were analysed at the entrance and exit of the system to give an overview of any contamination issues.

The health of the ecosystem and the future of agriculture are two highly interrelated and important goals. As such, it is important to try to identify the cause(s) of the degradation of the marshes, and use adaptive management strategies to deal with this, while ensuring the economic future of the area. In order to achieve this it is vitally important to have valid scientific information on these issues.

38 II. Materials and Methods

1. Sample Sites The sampling sites for this project are listed in Table 1 and depicted spatially in Figure 1. All sites were sampled for nutrient analysis, while only those indicated were sampled for pesticide analysis.

Table 1: Name, location and land use of sampling sites. Site Water Way Site name Distance & Predominant Sampled number Direction Land use for from Warren pesticide (km) analysis 1 Macquarie Marebone weir Public River 44 N land √

2 Macquarie Oxley gauge Cattle - River 75N + 7E production

3 Bulgeragah Ck Cattle - Oxley Station 75N + 17E production

4 Macquarie Macquarie at Light - River Gibson’s Way 106 N+ grazing

5 Monkeygah Ck Monkeygah at Cattle Gibson’s Way 106 N+ production -

6 Bulgeragah Ck Bulgeragah at Public - Gibson’s Way 106 N+ grazing

7 Macquarie Pillicawarrina Cotton River bridge 116 N production -

8 Macquarie Burrima Marsh River 130 N √

9 Macquarie Bell’s Bridge 168 N Public land River √

39 This page left intentionally blank. Map will be inserted here. Figure 2: Map of the Macquarie Marshes showing the main tributaries and the nine sampling sites used in this study.

40 2. Sample collection Triplicate grab samples were collected at approximately 25cm below the water surface. Where water was less then 50cm deep the samples were collected at mid depth. Samples were collected in either 200 mL polyethylene bottles (for nutrient analysis) or 1 litre glass bottles with Teflon lids (for herbicide analysis). Samples were then transported back to the university and stored in a cool room at 4◦ and analysed as soon as possible.

The pH and electrical conductivity (EC) was also measured in triplicate at each sampling site, on each occasion. A calibrated combined Horiba pH EC meter (D-54 pH/COND) was used for this.

3. Sample Preparation Samples for nutrient analysis were filtered through Watman No 5 filter paper if required before being analysed.

4. Sample Analysis Samples were analysed for orthophosphate and nitrogen by FIAstar 5000© Flow Injection Analyser. With standard methods as shown in the FIAstar5000© manual and repeated in part below. For operational methods please see the FIAstar5000© manual.

1. Nitrogen Process: The nitrite and nitrate concentration was analysed by FIAstar 5000 © flow injection analyzer. The sample was diluted by in line dialysis. The nitrate in the sample is reduced to nitrite in a cadmium redactor. With the addition of sulphanilamide solution nitrite present forms a diazo compound. This is then coupled with N-(1-naphtyl) Ethylene diamine Dihydrochloride to form a purple azo dye. This colour is then measured at 540 nm

Apparatus: • FIAstar 5000 analyzer unit • Dialysis method cassette NO2/NO3 + interface filters M=540nm and R=720nm 41 • 5027 Sampler • Prepacked columns • Volumetric flasks of nominal capacity 100 mL, 500 mL and 1000 mL. • Pipettes of nominal capacity 0.2-10 mL • pH electrode

Reagents: A. Ammonium Chloride buffer – pH 8.5 (carrier solution and reagent) 85g of Ammonium chloride was dissolved in 500 mL of distilled water. 7.5 mL of ammonia was added to bring the solution to pH 8.5. The resultant solution was then diluted to 1000 mL with distilled water.

B. Sulphanilamide 5 g of sulphanilamide was dissolved in 250 mL, to which 25 mL of concentrated hydrochloric acid was added. This was then diluted to 500 mL with distilled water.

C. NED reagent 0.5 g N-(1-naphtyl)Ethylene diamine Dihydrochloride was dissolved in 500 mL of distilled water.

D. Nitrite stock standard solution 6.068 g of Sodium Nitrate was dissolved in 1000 mL of distilled water.Calibrating solutions The following calibrations were used: Table 2: Calibration solutions for nitrogen analysis NO3-N concentration Volume of stock standard Final volume (mg/L) solution (mL) (mL) 0 NP water 100 2 0.2 100 5 0.5 100 10 1 100 20 2 100 50 5 100 2. Orthophosphate

42 Process: The sample reacts with ammonium molybdate to form heteropoly molybdophosphoric acid. The acid is then reduced to phosphomolybdenum blue by stannous chloride in a sulphuric acid medium. The intensive blue colour of the heteropoly compound is measured at 720nm.

Apparatus: • FIAstar 5000 analyzer unit • Method cassette P + interface filters M=720nm and R=1000nm • 5027 Sampler • Volumetric flasks of nominal capacity 25 mL, 100 mL, 250 mL and 500 mL. • Pipettes of nominal capacity 0.2-10 mL

Reagents: A. Ammounium Molybdate 5 g of ammonium molybdate was dissolved in approximately 250 mL of nanopure (NP) water and transferred to a 500 mL volumetric flask. 17.5 mL of concentrated sulphuric acid was added and mixed. The solution was made up to volume with NP water.

B. Stannous chloride 1 g of hydrazinium sulfate and 1 g of stannous chloride was dissolved in 250 mL of NP water and transferred to a 500 mL volumetric flask. 14 mL of concentrated sulphuric acid was added and mixed. The solution was made up to volume.

-1 C. Stock standard solution (100mg L PO4-P) 0.1098 g of potassium dihydrogen phosphate was dissolved in NP water and transferred to a 250 mL volumetric flask. The solution was made up to volume.

-1 D. Interim stock standard solution (5000µg L PO4-P) 5 mL of the stock standard solution was pipetted to a 100 mL volumetric flask and made up to volume with NP water. This solution was used to prepare the calibrating solutions. 43

E. Calibrating Solutions Table 3: Calibration solutions for orthophosphate analysis PO4-P concentration Volume of interim stock Final volume with NP (µg L-1) standard solution (mL) water (mL) 0 NP water 25 200 1 25 400 2 25 600 3 25 800 4 25 1000 5 25

3. Total Phosphorus Total Phosphorus was analysed using the HACH digestion block and the UV spectrometer. The standard per-sulfate digestion method was used and is repeated below in part. For operational instructions for the UV spectrometer please see the user manual.

Process: Total phosphorus includes all orthophosphates and condensed phosphates, dissolved and particulate, organic and inorganic. Digestion and oxidation releases phosphorus from combination with organic matter (APHA 1985)

Apparatus: • HACH digestion block • Digestion tubes • Hotplate and magnetic stirrer • UV spectrometer • Test tubes • Pipettes • Volumetric flasks of nominal volume 100 mL, 250 mL, 500 mL and 1000 mL

Reagents A. Digestive reagent

44 For 300 mL of digestive reagent 1.38 g of sodium hydroxide and 27 g of potassium persulfate were dissolved in a 300 mL volumetric flask and mixed on a hot plate stirrer. The reagent was then cooled before using.

B. Standard solution (50 mg-P L-1) 219.5 g of anyhydrous KH2PO4 was dissolved in a 1000 mL volumetric flask. This solution was then made up to volume.

C. Stock standard solution (2.5 mg-P L-1) 5 mL of the above standard solution was diluted to 100 mL in 100 mL volumetric flask. Table 4: Calibration solutions for nitrogen analysis P Concentration Volume of stock standard Final volume (mg/L) solution (mL) 0 NP water 100 0.01 0.4 100 0.03 1.2 100 0.05 2 100 0.08 3.2 100 0.1 4 100 0.2 8 100

D. Combined reagent The following reagents were made and then combined to form the combined reagent which reacts to with the sample to form a colour that is measured by the spectrometer.

I. Sulfuric acid solution 50 mL of NP water was added to a 1000 mL volumetric flask. To this 134.2 mL of concentrated sulfuric acid was added and carefully mixed. After the solution had returned to room temperature it was diluted to volume.

II. Ammonium molybdate solution 20 g of ammonium molybdate was diluted in a 500 mL volumetric flask.

III. Ascorbic acid solution

45 1.76 g of ascorbic acid was dissolved in a 100 mL volumetric flask and made up to volume.

IV. Potassium antimonyl tartrate solution 1.3715 g of Potassium antimonyl tartrate was dissolved in a 100 mL volumetric flask and made up to volume.

To prepare 100 mL of combined reagent the above reagents were allowed to reach room temperature and then were mixed in a 200 mL conical flask in the following ratio and order. 1. 50 mL of sulfuric acid solution 2. 5 mL of potassium antimonyl tartrate solution 3. 15 mL of ammonium molybdate solution 4. 30 mL of ascorbic acid solution

Digestion of samples: 6 mL of each sample was mixed with 3 mL of digestive reagent in the digestive tubes. These were then placed in the HACH digestion block at 120°C for one hour.

Analysis of standards and samples: 9 mL of sample/standard was transferred to a test tube. 1.5 mL of combined reagent was then added and mixed. The analysis was performed 15 minutes after this addition.

4. Total load To determine total load it is necessary to obtain flow data for the corresponding sites. This data was obtained from the Department of Natural Resources website as discharge in mega litres (ML) per day. The total load was calculated for each site and time period using the following formula (EPA 2007).

Ld = Cd × Vd Where

Ld = day's observed load of the pollutant (kg) -1 Cd = concentration of the pollutant on the day (mg L )

Vd = day's total volume of discharge (ML).

46

The total load was calculated for nitrogen, total phosphorus and total salt (as determined from the observed electrical conductivity). The following formula was used to determine total salt load.

Cd = 0.68*EC (µS/cm) The concentration was then used in the above total load formula.

5. Pesticide Concentration The concentration of Atrazine, Fluometrin, Diuron and Metachlor were analysed with LC-MS-MS at Agrisearch Analytical, a NATA accredited commercial laboratory. An “Agulent zorbax eclipse plus” C18 column (dimensions 2.1mm x 150mm x 1.8µm) was used, with a detection limit of 10ppb. The multiple reaction monitoring (MRM) range is shown below for each herbicide. The first range is used to quantify the concentration, the second to distinguish between the herbicides.

Table 5: MRM quantifying and distinguishing range for the pesticides analyzed using LC-MS-MS. Herbicide MRM Quantifying range MRM Distinguishing range Metachlor 284-252 284-176 Fluometron 233-160 233-72 Diuron 233-160 233-72 Atrazine 216-174 216-132 Preliminary herbicide analysis was only conducted on the samples from Marebone Weir and Bell’s Bridge (January and February) and Marebone weir and Burrima (April and September) to give an overview of the concentrations entering and exiting the system.

47 III. Results

A summary of the nitrogen and total phosphorus concentrations organised by site and month are shown in Figure 3 to display the results in a spatial and temporal context. For clarity, only values that exceed the ANZECC (2000) trigger levels are shown.

The section will also present the results from analysis in graphical and tabular form, with concentration values given in µg L-1 or mg L-1 for ease of reading. Figures showing the average concentration also contain the ANZECC trigger value for local ecosystem protection to enable easy comparison with results. The total phosphorus (P), nitrogen (N) and salt loads are also presented in Kg of observed daily load for the four sites at which flow data was available.

Each graph shows error bars that correspond to the standard deviation of triplicate determinants.

None of the four common herbicides tested for were above the detection limit of 10ppb.

48 This page left intentionally blank map will be inserted here.

Figure 3: Map of sites showing the average nitrogen (N) and average total phosphorus (TP) concentrations (all in µg L-1) that exceeded the trigger values of 500 and 50 µg L-1 respectively. A dash represents a value below trigger value.

49 1. pH and Electrical conductivity Table 6 shows the average pH and EC values for each sampling occasion. There is a general increase in pH from February to April. The ANZECC upper trigger value for pH of lowland rivers is pH 8. Table 6 shows that this pH is exceeded at all of the sites except Burrima at least once, often by more then 0.1 of a pH unit. Table 6 also shows that the EC at each sampling occasion is greater then 300 µS/cm, the level at which care should be taken when used for irrigation. Only Pillicawarrina in September exceeds the 800 µS/cm value for good quality drinking water. All sites are suitable for livestock consumption (ANZECC 2000).

Table 6: Average pH and electrical conductivity for each site at each sampling occasion, as measured in the field. Average pH Average EC (µS/cm) Site Jan Feb Apr Sept Jan Feb Apr Sept Marebone weir 7.1 8.1 7.2 7.9 403 351 429 -

Macquarie R at Oxley St 7.0 8.1 7.7 7.9 432 356 474 632

Bulgeragah Ck at Oxley St 7.9 8.9 8.3 8.7 399 359 439 -

Macquarie R at Gibson’s 7.2 8.3 - - 529 488 - - Way

Monkeygah Ck at 7.6 7.8 8.1 7.1 479 424 583 620

Gibson’s Way

Bulgeragah Ck at Gibson’s 7.0 9.1 8.3 - 428 443 454 - Way

Pillicawarrina bridge 7.8 7.3 8.3 8.1 422 492 485 919

Marsh at Burrima 6.9 7.8 7.5 7.9 690 957 564 -

Macquarie R at Bells 7.1 8.9 - - 490 379 - - Bridge

50 2. Nitrogen Nitrogen in this report refers to both nitrite and nitrate, the available pool, not total nitrogen. Ammonium was not included in the analysis as it quickly degrades to nitrate and is difficult to detect. The average nitrogen (N) concentration (mg L-1) for each sampling period and site are shown in Figure 4. This figure shows that five of the 36 (13.9%) averages exceeded the trigger value, 4 of which were more then double the value of 0.5 mg L-1. The two highest peaks also display the greatest standard deviation.

3. Orthophosphate The average orthophosphate (OP) concentration (µg L-1) for each sampling period and site are shown in Figure 5. This figure shows that 8 of the 36 averages exceeds the trigger value, four of which are more then five times higher then the trigger value of 20 µg L-1. A significant peak occurred at the Monkeygah Creek in April, at Burrima and Bell’s bridge in February. There was also a peak in January at Burrima, however, this sampling site/time is characterised by large standard deviations.

4. Total Phosphorus The average total phosphorus (TP) concentration (µg L-1) for each sampling period and site are shown in Figure 6. It can be seen that only 6 of the 36 averages do not exceed the trigger value of 50 µg L-1. The occurrence of high concentrations (twice the trigger value) of TP is spread over the sites and sampling periods, with the February sampling period showing the largest number of extremely high peaks (4 or more times greater then the trigger value).

51 Nitrogen as nitrate/nitrite

10

9

8

7

6

5

4

Concentration (mg/L) 3

2

1

0 Marebone weir Oxley gauge (2) Bulgeraga Ck Gibosn's Way Monkeygah Ck Bulgeragah Ck Pillicawarrina Burrima (8) Bell's Bridge (9) (1) at Oxley (3) (4) at Gibson's at Gibson's (7) Way (5) Way (6)

Figure 4: Average nitrogen (combined nitrate and nitrite) concentration for all sites and sampling periods (site numbers shown in brackets). Also shown is the ANZECC local ecosystem trigger value of 500µg L-1. Error bars show standard deviation of triplicate determinations. * Data not available at sites 4 & 9 in April or September.

52 Orthophosphate

600

500

400

300

200 Concentration (µg/L)

100

0 Marebone weir Oxley gauge Bulgeraga Ck Gibosn's Way Monkeygah Ck Bulgeragah Ck Pillicawarrina Burrima (8) Bell's Bridge (9) (1) (2) at Oxley (3) (4) at Gibson's at Gibson's (7) Way (5) Way (6)

Figure 5: Average orthophosphate concentration for all sites and sampling periods (site numbers shown in brackets). Also shown is the ANZECC local ecosystem trigger value of 20µg L-1. Error bars show standard deviation of triplicate determinations. * Data not available at sites 4 & 9 in April or September.

53 Total Phosphorus

1000

900

800

700

600

500

400

Concentration (µg/L) 300

200

100

0 Marebone weir Oxley gauge Bulgeraga Ck Gibosn's Way Monkeygah Ck Bulgeragah Ck Pillicawarrina Burrima (8) Bell's Bridge (9) (1) (2) at Oxley (3) (4) at Gibson's at Gibson's (7) Way (5) Way (6)

Figure 6: Average total phosphorus concentration for all sites and sampling periods (site numbers shown in brackets). Also shown is the ANZECC local ecosystem trigger value of 50µg L-1. Error bars show standard deviation of triplicate determinations. * Data not available at sites 4 & 9 in April or September.

54 5. Total load It is important to note that no load data was able to be calculated for the site at Bell’s Bridge in April and September due to the lack of water. The concentration data shown in Figure 4, 5 and 6 was used to calculate the nutrient load averages, whilst the EC data shown in Table 5 was used to calculate the total salt load.

The observed daily average total phosphorus load (TPL) is shown in Figure 7. The January sampling period shows a decrease in TPL over distance, while the February sampling period shows a large decrease at Oxley gauge and then a large increase at the marsh site, Burrima. The April and September loads, in contrast, are quite low. Figure 8 shows that the orthophosphate load also decreases from Marebone weir to Oxley gauge and then increases at Pillicawarrina in January and February. A large decrease can then be seen at Bell’s Bridge in both January and February. Again the load in April and September were quite low.

Figure 9 shows the observed daily average nitrogen load (NL). The April and September periods had no NL, whilst all sites during January showed a NL of greater then 4 kg per day. The one site in February that returned a NL had a daily load of 37.5 kg.

The total salt load (TSL) data set, as shown in Figure 10, has the smallest standard deviation of the three data sets, although the observed daily load is significantly higher then the observed TPL and NL. The TSL in January and February shows a decreasing trend. There is a very large difference in the TSL during these first two sampling periods and the third in April. EC data was only available for the one site shown during the September sampling period.

55 Total Phosphorus Load January Febuary April 10 September 9

8

7

6

5

4

3 Observed Daily Load (Kg) Daily Observed 2

1

0 Marebone weir (1) Oxley gauge (2) Pillicawarrina (7) Bell's Bridge (9)

Figure 7: Average observed daily phosphorus load in Kg, at the four sites at which flow data was available. Error bars show standard deviation of triplicate determinations. * Data not available at Bell’s Bridge in April or September.

Orthophosphate Load January February 4.5 April September 4.0

3.5

3.0

2.5

2.0

1.5 Daily Observed Load (kg) Observed Daily 1.0

0.5

0.0 Marebone weir (1) Oxley gauge (2) Pillicawarrina (7) Bell's Bridge (9)

Figure 8: Average observed daily orthophosphate load in Kg at the four sites at which flow data was available. Error bars show standard deviation of triplicate determinations. * Data Not available at Bell's Bridge in April or September. 56 Total Nitrogen Load January Febuary April 120 September

100

80

60

40 Observed Daily Load (kg)

20

0 Marebone weir (1) Oxley gauge (2) Pillicawarrina (7) Bell's Bridge (9)

Figure 9: Average observed daily nitrogen load in Kg, at the four sites at which flow data was available. Error bars show standard deviation of triplicate determinations. * Data not available at Bell’s Bridge in April or September.

Total Salt Load January February 50 April

45 September

40

35

30

25

20

15 Daily Observed Load (tonnes) Load Daily Observed 10

5

0 Marebone weir (1) Oxley gauge (2) Pillicawarrina (7) Bell's Bridge (9)

Figure 10: Average observed daily salt load in tonnes, at the four sites at which flow data was available. Error bars show standard deviation of triplicate determinations. * Data not available for Bell’s bridge in April or September 57 IV. Discussion

Wetlands have an inherent value as habitat but are also commonly thought to increase the water quality downstream through reduced nutrient, sediment and salt levels, and as such are often credited as filtering mechanisms. Growing wetland vegetation actively removes nutrients from the water column and provides an environment conducive to sedimentation (Brady and Riding 1996). In recent years, constructed wetlands have become a recognised method of reducing pesticide concentrations in runoff derived from agricultural areas (Schulz 2004). The potential for biological and chemical transformation of pesticides is increased by the decreased flow rates and the increased plant and microbial biodiversity of wetland systems (Angier et al. 2002; Roberts 1998; Rose et al. 2006; Stangroom et al. 2000). Decreases in pH, turbidity, electrical conductivity (EC) as well as nitrogen and phosphorus loads after passage through a constructed wetland has been recorded by Finlayson et al., (1986). A similar effect is expected in the Macquarie Marshes, however previous data has pointed to a system that does not exhibit this trend (DNR, 1993-99).

This study was particularly focused on the water quality of the marsh system and its ability to filter and remove nutrients as expected. In order to asses this, the study investigated the water quality and load characteristics of the Macquarie Marshes, with an emphasis on the affect of agricultural land use on nutrient concentration and load. The water quality of the system was determined by comparing pH, EC, and the concentration and load of nitrogen (N/NL), orthophosphate (OP) and total phosphorus (TP/TPL) to the ANZECC (2000) low land river trigger values. The ANZECC trigger values are calculated for the major climatic zones of Australia and are the accepted guidelines for water quality measurement and monitoring in Australia and New Zealand. The trigger values stated in the results section for N, OP and TP are used to assess the risk of adverse effects due to nutrient pollution. A concentration of a nutrient above the specific trigger value indicates the potential for algal growth which can have severe detrimental effects on stock, humans and natural ecosystems. Hence, the trigger values are an important indicator of water quality and risk of degradation, and should be used as such. Trigger values and associated concentration data do not, however, give necessary insight into the mechanics of a system as complex as the Macquarie Marshes which is required to

58 determine if the marsh is acting as a filter. The effects of decreased flow over distance and time, as well as the decreased volumes associated with a highly channelised and pooled wetland, are not taken into consideration by concentration data. Studies on constructed wetlands focus on the amount (load) of nutrient removed from the system, as it is a better indicator of the filtering capacity. As such, this section aims to combine concentration and load data over four sampling periods in a dry year to determine the effects of land use on water quality and the overall health and functioning of the system.

This is not to negate the importance of individual sites remaining below the accepted nutrient trigger values, as a concentration greater then the trigger value means there is a risk of algal blooms, regardless of the total load or volume of the water way. However, a complex system such as this necessitates a whole system approach, rather than a site by site assessment.

Given that this study considers on the effects of land use on water quality, large peaks in all nutrient parameters were expected to occur at Oxley station and Monkeygah Ck due to intense cattle grazing, especially in the sampling periods of April and September. However, a large peak was not expected at Pillicawarrina farm due to the extent to which runoff, and therefore erosion, from the farm is controlled. An increase in all nutrient parameters was also expected between the furthermost sites: Marebone Weir and Bells Bridge.

1. Nitrogen concentration Nitrogen is one of the limiting factors for algal growth in Australian rivers and is closely monitored. A nitrogen source can cause large problems with nuisance plants, including algae (Whittington 1999). “Nitrogen” in this report refers to both nitrate and nitrite. The majority of the available nitrogen in the water column is generally nitrate (Richardson and Vepraskas 2001), but it is not possible to determine the major species in this situation as the nitrate is converted to nitrite before analysis. Sites that exceed the trigger value of 0.5 mg L-1 are not considered to be nitrogen limited and have the potential to develop algal blooms.

59 Figure 4 shows that generally the nitrogen concentration was well below the trigger value. A common trend is not seen over the four sampling periods, with February the only period to exhibit a strong trend over the sites. This period shows an increasing trend between the parallel sites on Gibson’s Way (Monkeygah Creek and Bulgeraga Creek) and the marsh site at Burrima (see map, Figure 2). The concentration at Monkeygah Creek is well below the trigger value, which is not unexpected because there was very little cattle activity observed in the area during sampling. The increased peak shown at Pillicawarrina in this sampling period can most likely be attributed to the convergence of the three sites (Macquarie River, Monkeygah Ck and Bulgeraga Ck) at Gibson’s way directly upstream of this site. This site does not show a peak during the remaining three sampling periods when the upstream concentrations are all close to zero, indicating this peak is a result of additions rather than a point source of N.

The February and April concentrations of the Bulgeraga Creek at Gibson’s way are higher then that of the same creek at Oxley station, approximately 50kms to the south. This indicates that either there is nitrogen entering the system between the two sites or there are large enough evaporation losses to concentrate any nitrogen in the water column. This could be determined by measuring the flow/volume of water at the two sites (see section on loads, below).

Additionally, there is a nitrogen peak at the marsh site, Burrima during the first three sampling periods. During the January sampling period the concentration then dramatically reduced at the furthermost site, Bell’s Bridge. There was also a decrease in February; however the concentration is still above the trigger value. Because of the lack of water at Bell’s Bridge in April and September at this site, it was not possible to determine if either of these observations are trends or isolated events. The lack of water also makes comparisons between the two furthermost sites difficult. In January, there was not a noticeable difference between the concentrations at the two sites. Comparatively, in February the concentration was significantly higher than at Marebone weir, as expected form previous data. This is in agreement with the DNR data, although it is not a conclusive trend, due to the limited repetition.

60 The peak at the Monkeygah Creek in April (Figure 4) is important, as it corresponds with the presence of cattle grazing directly in the waterway. Bank erosion, vegetation removal and pugging were observed at the site, indicating an increase in sediment disturbance and addition to the water column by the livestock. This increase in bank erosion and movement of organic matter could contribute significant amounts of nitrogen to the water column as nitrogen is transported in soil organic matter and as nitrate or ammonium attached to sediment (Follet & Delgado, 2002). This also agrees with the observations made by Coveney et al. (2002) that disturbances to sediment layers dramatically increase water column nutrient levels. Grazing directly in waterways can also cause an increase in N concentration due to excrement. Follet and Delgado (2002) report that a steer which ingests 180 g of nitrogen will excrete 160g, 74% of which is dissolved in urine. This site had a non detectable N concentration in the September period, despite grazing being observed at this time, although to a lesser extent and around the perimeter of the sampling site. As such, the grazing at this time would have contributed very little nutrient to the water column, through either erosion or fecal matter. The water level at the September period was observed to be higher than that at the April sampling, which would also affect the N concentration because of dilution.

Follet and Delgado (2002) states that selective detachment of fine sediments containing bound NH4 leads to a high concentration of total nitrogen in the water column, and as such, the nitrogen data shown above may be an underestimation of the available nitrogen, if the erosion has occurred recently and the ammonium has not degraded to nitrate.

2. Total Phosphorus Phosphorus exhibits low water solubility and has a tendency to bind to soil particles suspended in the water column (Richardson and Vepraskas 2001). The sedimentation of these particles effectively removes the phosphorus from the water column, resulting in phosphorus being the most limiting nutrient for many types of algae (Johnston et al. 2004). As there is no gaseous phase of phosphorus, all inputs are from phosphorus- bearing sediment, animal waste, decomposing organic material or re-release from the sediment layer because of disturbances or anoxic conditions (Richardson and Vepraskas 2001). The largest source of P is considered to be from highly fertilised agricultural soils when storm flow paths allow run off to reach water ways (Kurz et al. 2001). Arnscheidt 61 and Jordan et al. (2007) state that the magnitude and fraction of the P transferred to waterways is dependent on the hydrological flow paths and surrounding land use.

Total phosphorus (TP) is composed of dissolved and suspended organic and inorganic components (Clesceri et al. 1998). Total phosphorus is important when assessing the overall health of the waterway but does not indicate how much phosphorus is available for direct biological uptake as it includes the unavailable organic fraction (Richardson and Vepraskas 2001). The ANZECC trigger value for total phosphorus is 50 µg L-1.

Unlike the N concentrations, TP concentrations often exceed the ANZECC trigger value. Only six of the 36 averages are less then the 50 µg L-1 trigger value (Figure 6). A similarity however, is the trend in February for increasing concentration with distance. An increase from Marebone Weir to Bell’s bridge can be seen in the Macquarie River system and an increase is also noted between the two sites on the Bulgeraga Creek. Pillicawarrina shows a high concentration in January and February; both of which could be attributed to addition at the convergence, as discussed above. In contrast, the April and September data show a lower concentration at Pillicawarrina than both of the sites at Gibson’s Way. The lower volumes of water at all sites in April and September suggest that the concentration increase would be more pronounced between these sites due to concentration of the nutrient in the water column.

The peak in TP at the marsh site Burrima, in January mirrors the peak seen in N at the same sampling time, although it is important to note that due to access problems, the site sampled in January was not the same site which was sampled for the rest of the study. The January site was on the edge of the marsh area and was not as deep or quick flowing as the site used in the rest of the study. This and the high standard deviation of both points, means that these values should be used with caution. It is important to note the large variation of flow volume and regime within a small area of marsh system, and the difficulties that arise in a study such as this when sampling in a complex area. An explanation for the high levels of TP may be due to the decomposition of organic matter, up to 54% of the initial P content of vegetation can be released in 12 days (Wang and Mitsch, 2000).

62 The TP concentration of the Monkeygah Creek at Gibson’s Way and the Bulgeraga Creek at Oxley station exceeded the trigger value of 50 µg L-1 at all four sampling periods. Cattle grazing was heaviest at these two sites through out the study period and a high concentration of both OP and TP was expected because of the observed erosion and disturbance of the water ways. Topsoil is the fraction of the soil highest in orthophosphate due to fixation and as such any erosion caused by grazing at the site will cause an increase in OP concentration, as sediment is transferred to the water column, into which orthophosphate rapidly desorbs (Wang and Mitsch, 2000). Despite this, the OP trigger value (20 µg L-1) was only exceeded twice at Monkeygah Creek (128 µg L-1 in April and 35 µg L-1 in January) and not at the Bulgeraga. This indicates that the main phosphorus pools at these two sites, excluding the Monkeygah in April, is fixed mineral phosphorus- orthophosphate bound to an Al3+ or Fe3+ oxide or hydroxide or bound to Ca2+ or Mg2+ cations; or organic phosphorus- in plant compounds and bound to organic molecules in the sediment. These pools make up 63% to 89% of the total phosphorus at the Monkeygah (excluding April) and 91% to 100% at the Bulgeragah. The OP concentration makes up 98% of the TP in the April period at Monkeygah Creek. This data generally agrees with Richardson and Vepraskas (2001) who state that these two unavailable pools generally comprise 80-90% of the P in a wetland, indicating that the addition of available phosphorus through excrement and erosion is negligible, except in April at the Monkeygah. In April cattle were observed to be actually in the waterway, rather than gathered at the perimeter, as in the other sampling periods. The water was also observed to be much more turbid and contain more fecal matter in this period. These sites did not, at this stage, present a risk of algal growth, as the two major pools are biologically unavailable to algae. However, the other environmental problems associated with erosion should be considered in management strategies for these sites.

3. Orthophosphate Orthophosphate is the biologically available fraction of phosphorus (Johnston et al. 2004). This is the fraction that is available to aquatic biota and to aquatic plants. OP concentration is important, as it is easily used by nuisance plants such as algae that are potentially toxic and senesce when the nutrient source has been depleted, dramatically changing the aquatic environment. As such, the trigger value for orthophosphate concentration is quite low at 20 µg L-1. As the easily accessible fraction of the total 63 phosphorus pool, any large additions through erosion or disturbance upstream should theoretically be removed from the water column in the highly vegetated marsh area. This has been observed in constructed wetlands in Australia (Finlayson et al. 1986) and in natural reed beds where the total phosphorus concentration was decreased from 0.5 mg L- 1 to less then 0.005 mg L-1 (Headley et al. 2003).

The orthophosphate data (Figure 5) shows similar trends to the nitrogen data. The February averages follow a similar trend to that seen in the N and TP graphs (Figure 4 and 5), increasing from the sites at Gibson’s Way (Macquarie River, Monkeygah Ck and Bulgeragah Ck) to the final site at Bell’s Bridge. The February sampling period is the only period to exhibit a high concentration at Pillicawarrina, again indicating additions at the convergence of the three waterways. Unlike the nitrogen data, however, the OP concentration increases from Burrima to Bell’s Bridge, indicating either addition to the system, or significant evaporation losses. The distance between the two sites and the climate of the area makes this a realistic explanation. This will be further investigated with relation to total load in the next section.

Figure 5 also shows that the Macquarie River at Oxley gauge exceeds the trigger value (25 µg L-1); however, as the standard deviation of this point is twice the average it is not an accurate representation of the OP concentration.

Although a relationship between stream flow and phosphorus concentrations is a generally expected trend (Tunney et al. 1998) no relationship was found in this study between flow and concentration when a regression analysis was undertaken. The data did not fit any available model.

4. Total Load While the concentration data, as shown above, can determine sites which exceed the trigger values, and therefore need investigating, the one dimensional nature of the data leaves many unanswered questions. Is the increase in concentration because of increased pollution or decreased water flow or a combination of both? To address these questions, the total load of phosphorus, nitrogen and salt traveling through the system were calculated for each sampling period. The total load is the amount of nutrient that passes 64 the sampling point, which requires the flow of the waterway to be taken into account. This data gives an additional layer which enables the system to be assessed as a whole. Importantly, it also highlights the inaccuracies associated with drawing inferences from a non suitable data set.

As the loads shown in Figure 7, 8, 9 and 10 are essentially a (simple) mass balance model, it is important to have a conceptual idea of the system in question. Figure 11 shows a simple conceptual model of the Macquarie Marsh system. The four sites with available flow data are shown, together with the routes of the three waterways studied. The red arrows indicate losses from the system (through significant channels or streams and evapo-transpiration) that can not be quantified. The total load was calculated at the four sites shown which encompass the Macquarie River and its major tributaries.

65 N

Figure 11: Simple conceptual model of the Macquarie Marsh system studied, showing the four points at which load was calculated and the inputs and out puts of the system. Red arrows are losses that cannot be accounted for in this study. While Rainfall run off is recognized here it has not been used in load calculations. 66 The load indicates losses from, or additions to the system, as concentration and flow are inversely related. This is easily visualized with the following scenario: Point A has a certain concentration and flow, and therefore load: L = F x C Eg: 0.04 mg/L x 149 ML = 6.5Kg

As the flow decreases to that observed at site B, in this example 100ML, the load can either be observed to: increase, decrease or stay constant as shown below. 1. A constant load will be observed if the increase in concentration is in proportion to the decrease in flow: 0.065 x 100 = 6.5 kg

2. A decrease in load will be observed if the concentration stays constant, decreases or increases at a smaller rate then the flow decreases: 0.04 x 100 = 4 kg (< 6.5) 0.03 x 100 = 3 kg (<6.5) 0.06 x 100 = 6 kg (< 6.5)

3. An increase will only be observed if the concentration increases at a larger rate then the flow decreases: 0.06 x 100 = 6 kg < 6.5 0.07 x 100 = 7 kg >6.5

Scenario 1 given above would occur in a controlled, closed system such as a concrete pipe where no additions or losses of the nutrient can occur. In a system such as the Macquarie Marshes, where there are areas of actively growing vegetation and areas of active erosion, the remaining two scenarios are both possible. The load therefore, will be used as an indicator of the filtering capacity and health of the system.

From the concentration data shown in Figures 4, 5 and 6 it would be easy to come to the conclusion that, since the concentration of nitrogen and phosphorus were increasing instead of decreasing after the Macquarie Marshes, there is a problem with the functioning of the system. This has been done in the past with agriculture, both cotton and beef production, given as the cause of the degradation. This inference is highly 67 contradictory to the trends shown in Figures 7, 8, 9 and 10 and can be costly to the reputation of agriculture and individual enterprises.

(a) Total Phosphorus load Figure 7, the total phosphorus load as determined by the observed flow and calculated concentration, shows a decrease in load at all four sites. In January, 0.6 kg of TP passed through the Bell’s Bridge sampling site, compared to 5.4 kg at Marebone weir: a loss of 4.8 kg. In February the load decreased by 7.1 kg between the first two sites, and then increased by 3.1 kg at Pillicawarrina. This indicates that the concentration increase noted in the total phosphorus graph at this site (Figure 6) occurred at a greater rate than the flow decrease between the two sites. However, once this water traveled through the northern marsh system, the total load was decreased to 0.04 kg, a loss of 3.3 kg. So although the concentration at Bell’s Bridge in February is significantly higher then the concentration at Marebone weir, the large reduction in load, 7.3 kg over the whole system, indicates that the marsh system is functioning and removing TP from the water column. This removal is most likely due to either sedimentation, or uptake from the water column by phytoplankton and periphyton (Wang and Mitsch 2000). These organisms are extremely important, as most P utilized by common wetland plants (not algae) is absorbed from the sediment, not the water column (Carignan and Kaill 1980). It is the presence of the vegetation, however, which stabilizes the banks and slows the flow of the water, to allow sedimentation and the survival of these organisms. The complexity involved with numerous sources being modified by in-stream ecological and physical processes can make unraveling low flow phosphorus contribution a problematic undertaking, as recognised by (Jarvie et al. 2004).

Figure 8 shows that the orthophosphate load follows a similar trend to the total phosphorus in the January and February sampling periods. Again, as expected an increase in load is seen at Pillicawarrina, but importantly this is then reduced with passage through the marsh area. Available phosphorus is removed from the water column by sedimentation as well as direct removal by aquatic plants such as Azolla and also by phytoplankton (Wang and Mitsch 2000).

68 (b) Nitrogen load The nitrogen load (Figure 9) also shows a decrease between the two furthermost sites in January and February. An increase was seen at Pillicawarrina during both periods, again corresponding to high peaks in N concentration. The trend continues, with a large decrease in N load at Bell’s Bridge in both periods. The northern marsh has decreased the load from Pillicawarrina by 60 kg in January (93%) and 37 kg in February (99%). This removal is probably because of both plant removal and microbial activity. Angier et al. (2002) states that anaerobic conditions and high organic carbon levels provide mechanisms, generally de-nitrification, by which nitrate can be removed from the water column. Hunter et al. (2001) reports that although microbial activity is the accepted nitrogen removal pathway, their study showed that N removal was 38% greater in microcosms containing vegetation, and as such plant uptake may be more important than previously thought. Finlayson et al. (1986) state that nitrogen removal efficiencies of wetlands vary from 90% to net release; with this data sitting at the top of this range, it is a good indication that the highly vegetated, high in organic carbon, marsh system is functioning as a filtering mechanism.

(c) Salt load Figure 10 shows that the total salt load, calculated as NaCl, follows the same general trend displayed by the TP and N loads. Again, the total load in the January and February periods are highest at all sites, noticeably so at Marebone weir and Oxley gauge. The total load decreased from Marebone weir to Oxley gauge in January, February and April. Again, the load increased at Pillicawarrina during February and April, but decreased in September. The general trend continues in February with a decrease at Bell’s Bridge, a loss of 3.9 tonnes of salt between the last two sites. In January, however, there was an increase of 1.1 tonnes of salt between the two sites. The lack of water flow to Bell’s Bridge in April and September does make it difficult to determine which, if either, of the occurrences is the common trend.

As the salt load shown in Figure 10 is calculated by use of the sodium chloride conversion number, the load data is not as representative of the actual salt load. Electrical conductivity is a measure of all ions in the waterway, not just the sodium and chloride ions. As such, multiplying this by 0.68 (conversion for sodium chloride) to calculate the 69 concentration (mg L -1 is an over simplification of the actual physical process. This method is commonly used in natural resource management though, and any inferences drawn from such data should be carefully considered, as different salts have different affects on ecosystems and agricultural enterprises. Conservative salts such as sodium, chloride and bromine can have extreme effects on plants, ecosystems, and agriculture. 2+ 2+ + - 2- Comparatively non-conservative salts such as Mg , Ca , K , HCO3 and SO4 , have a low solubility and are much less harmful then conservative salts (Herczeg et al. 2001). It has been suggested that, as waterways transport and drain either conservative salts, non- conservative salts or differing ratios of the two (Herczeg et al. 2001) that the sodium to chloride ratio of the water be used as an indicator (Conyers et al. 2007). This would allow better utilization of resources and give a more representative overview of the salt loads of waterways such as the Macquarie Marshes.

V. Future Research

This report highlights the importance of valid scientific data when drawing natural resource management conclusions, and also the difficulties associated with collecting samples to achieve this. An increase in the number of sites and sampling periods would also see an increase in the accuracy of the trends. As this is a constantly changing system data collection needs to occur week to week over a long period in order to capture the natural variation. This would ideally incorporate sampling in periods of high flow and peak storm events. The bulk of annual P transfers to water ways, are associated with sudden, infrequent, high intensity storms, (J. Arnscheidt et al. 2007) so this is a particularly important part of the system that could not be addressed in this study period. An increase in the samples taken from within the Southern and Northern Nature reserve would be valuable due to the large variation and differences within these areas.

A more complete understanding of the processes and possible pollution causes could also be achieved by determining the individual concentration of ammonium, nitrate and nitrite in the water column, as the different species originate from different pollutants. However such analysis was beyond the scope of this project.

70 The load calculations for the system are limited by the flow data that is available, which could possibly be overcome with the use of a portable flow meter, together with a determination of volumes. Total salt loads should be calculated as the addition of component ions rather than using the non accurate assumption that NaCl represents the total salt load. Again, this was beyond the scope of this project. Alternatively the sodium to chloride ratio could be used as an indicator of salinity as discussed above.

The most important recommendation that can be made is to approach the system as a whole, and to consider both individual site concentration data and the load data where available.

VI. Conclusions

The analysis of the concentration data showed that 14% of the sample averages exceeded the ANZECC 2000 environmental nitrogen trigger value of 500 µg L-1, 83% of the total phosphorus sample averages exceeded the trigger value of 50 µg L-1 and 22% of the available phosphorus averages exceeded the trigger value of 20 µg L-1. Increases in concentration at Pillicawarrina were due to additions from downstream sites due to the convergence of the water ways. Whilst increases in concentration of all parameters at the marsh site can be attributed to the decomposition of organic matter. Areas of high grazing pressure were shown to have higher than average orthophosphate concentrations in two of the four sampling periods, indicating the addition of available P due to disturbance of sediment and erosion. These sites that exceeded the trigger values should be monitored and investigated to prevent the growth of nuisance plants such as blue green algae.

No pesticides were detected at Marebone Weir, Burrima or Bell’s bridge as expected because of the low amounts of run off and cropped area adjacent to the marsh system.

Load calculations showed the increase in concentration was a result of evapo- concentration and the decrease in volume of water downstream. In January, 16.8 kg of nitrogen and 7.3 kg of total phosphorus were removed between Marebone Weir and Bell’s Bridge. Significant reductions occurred over the area of the Northern Marsh (60 Kg N in January and 37 Kg in February, and 3.3 Kg of TP in January). A significant 71 decreasing trend in salt load was also seen between these the two furthermost sites. This indicates that the marsh system is capable of filtering nutrients even in a low flow year. This study also highlights the importance of using appropriate data to make scientific and environmental recommendations. Both concentration and load data need to be considered to maximize the health and functioning of the system and the accuracy of any recommendations.

Whilst on concentration data alone it appears that the marshes do not add value with respect to nutrient removal, when load calculations are considered it is clear that significant removal is occurring and that the marsh system is a valuable natural resource.

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77 VIII. Appendix

Table 7: Nitrogen concentration results (mg/L) as obtained from analysis with FIAstar 5000. Site name and number Concentration mg/L January February April September Marebone weir (1) 0.26 0.00 0.03 0.00 0.03 0.03 0.000.00 0.05 0.00 0.000.00

Oxley gauge (2) 0.13 0.00 0.00 0.13 0.00 0.00 0.090.00 0.04 0.11 0.000.00

Bulgeraga Ck at Oxley (3) 0.00 0.00 0.00 0.07 0.00 0.02 0.000.00 0.00 0.01 0.000.00

Gibson's Way (4) 0.05 0.33 1.83 0.00 0.00 0.00 1.300.00 0.11 0.17 1.680.00

Monkeygah Ck at Gibson's Way (5) 0.28 0.20 0.00 0.00 0.39 0.00 0.310.00 0.26 0.03 0.040.00

Bulgeragah Ck at Gibson's Way (6) 0.00 0.17 0.00 0.00 0.00 0.08 0.030.00 0.00 0.95 0.040.00

Pillicawarrina (7) 0.00 1.06 0.63 0.13 0.13 1.06 0.510.00 0.00 1.08 0.620.00

Burrima (8) 7.67 3.02 0.00 0.18 3.27 4.04 0.000.00 7.56 3.08 0.000.00

Bell's Bridge (9) 0.22 3.25 0.13 0.00 0.06 4.02 0.000.00 0.10 0.50 0.000.00

78

Table 8: Orthophosphate concentration results (µg/L) as obtained from analysis with FIAstar 5000. Site name and number Orthophosphate Concentration (µg/L) January February April September

Marebone weir (1) 8.06 3.25 0.00 0.00 14.17 0.00 0.00 3.32 9.32 0.00 0.00 4.04

Oxley gauge (2) 0.00 3.87 0.00 3.49 0.00 0.00 3.27 0.00 0.00 0.00 73.110.00

Bulgeraga Ck at Oxley (3) 0.00 0.00 0.00 9.70 0.00 0.00 0.00 14.32 0.00 0.00 0.00 0.12

Gibson's Way (4) 0.00 8.44 171.59 6.73 4.75 8.66 125.5517.21 5.13 10.91 147.4216.43

Monkeygah Ck at Gibson's Way (5) 32.46 9.69 0.00 28.01 36.35 0.93 2.35 28.45 38.27 1.81 3.95 24.95

Bulgeragah Ck at Gibson's Way (6) 1.46 1.63 0.00 7.34 0.00 0.00 0.00 6.64 0.00 30.72 2.32 8.29

Pillicawarrina (7) 0.00 27.50 28.18 26.76 0.00 31.16 19.2413.07 0.00 31.56 26.0729.70

Burrima (8) 419.90 91.19 0.00 0.00 179.53 175.37 3.32 0.29 445.68 168.22 4.04 0.00

Bell's Bridge (9) 0.00 83.83 3.49 19.83 0.00 178.28 0.00 2.28 0.03 340.38 0.00 1.48

79 Table 3: Total phosphorus concentration results (mg/L) as obtained from per- sulfate digestions analysis Site name and number Total Phosphorus Concentration (mg/L) January February April September

Marebone weir (1) 0.04 0.03 0.06 0.07 0.04 0.03 0.07 0.10 0.03 0.04 0.05 0.12

Oxley gauge (2) 0.05 0.04 0.06 0.22 0.03 0.04 0.05 0.18 0.04 0.05 0.06 0.20

Bulgeraga Ck at Oxley (3) 0.08 0.07 0.21 0.09 0.05 0.06 0.08 0.10 0.03 0.07 0.05 0.10

Gibson's Way (4) 0.03 0.05 - - 0.03 0.04 - - 0.04 0.04 - -

Monkeygah Ck at Gibson's Way (5) 0.03 0.19 0.12 0.10 0.08 0.17 0.09 0.12 0.17 0.20 0.13 0.14

Bulgeragah Ck at Gibson's Way (6) 0.14 0.13 0.09 0.10 0.09 0.10 0.05 0.09 0.04 0.12 0.03 0.09

Pillicawarrina (7) 0.22 0.27 0.03 0.06 0.19 0.29 0.02 0.05 0.18 0.37 0.03 0.07

Burrima (8) 0.09 0.79 0.05 0.10 0.12 0.11 0.05 0.90 0.15 0.14 0.06 0.10

Bell's Bridge (9) 0.04 0.44 - - 0.05 0.44 - - 0.04 0.40 - -

80

Table 4: Mean daily discharge (ML/Day), used in load calculations, at the four sites at which the DNR measures and records flow data. Site name and number Mean Discharge (ML/day) January February April September

Marebone weir (1) 149.000 202.000 6.050 5.620

Oxley gauge (2) 30.000 5.700 1.900 5.538

Pillicawarrina (7) 11.800 10.550 7.020 0.003

Bell's Bridge (9) 13.728 0.110 0.00 0.000

81