Draft Version 1.2 December 2008

PREPARATION STATEMENT

The Mary Catchment Water Quality Improvement Plan (WQIP) was drafted by Dr Michael Walker, Water Management Officer, Mary & Burrum, Wide Bay Water Corporation. Funding for this task was provided jointly by the Burnett Mary Regional Group for Natural Resource Management (BMRG) and Wide Bay Water Corporation under a strategic partnership to improve water quality.

Dr Graeme Esslemont Water Quality and Equitable Use Coordinator (BMRG) assisted with editing the Mary Catchment Water Quality Improvement Plan (Draft 1.2), and with the condition assessments (chapter 2) and time series projections (chapter 3).

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Mary Water Quality Improvement Plan, Preparation Status

Document and Version Control

Document Title: Mary Water Quality Improvement Plan Client: Wide Bay Water Corporation and Burnett Mary Regional Group for Natural Resource Management Date Created: August 2007 Last Updated: December 2008 Authors: M Walker (Versions 1 and 1.1), G Esslemont (Version 1.2). Version: First draft

Version Control

Version Date and description Distribution 1 Partially completed first draft to BMRG WBWC WQIPs Mary & Burrum Steering Committee 15 9 Oct 07 Oct 2007 meeting postponed 1.1 Partially completed first draft to BMRG WBWC WQIPs Mary & Burrum Steering Committee 29 25 Oct 07 Oct 2007 1.2 Completed first draft to 15 BMRG WBWC WQIPs Mary & Burrum Steering Committee 15 Dec 08 Dec 2008

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CONTENTS

PREPARATION STATEMENT ...... i

ACRONYMS ...... vi

CHAPTER 1: Background to the Mary Water Quality Improvement Plan 1.1 UNITED NATIONS GLOBAL PROGRAMME OF ACTION ...... 2 1.2 NATIONAL WATER QUALITY MANAGEMENT STRATEGY ...... 2 1.3 FRAMEWORK FOR MARINE AND ESTUARINE WATER QUALITY PROTECTION……. 3 1.4 THE WATER QUALITY IMPROVEMENT PLANNING PROCESS…………………………. 4 1.5 THE GREAT BARRIER REEF WATER QUALITY PROTECTION PLAN (REEF PLAN)… 5 1.6 THE COASTAL CATCHMENTS INITIATIVE………………………………………………….. 6 1.7 THE REEF WATER QUALITY PARTNERSHIPS PROGRAMME (REEFPLAN)…………. 7 1.8 NATIONAL, STATE, LOCAL GOVERNMENT, AND NRM BODY PLANNING………………………………………………………………………………………… 9 1.8.1 The Wide Bay Burnett Coastal Management Plan………………………………….. 10 1.8.2 The Wide Bay Burnett Regional Plan……………………………………...... 10 1.8.3 The Great Sandy Region Management Plan………………………………………... 12 1.8.4 The Burnett Mary Regional Group for Natural Resource Management NRM Plan: Country To Coast – A Healthy Sustainable Future ...... 13

CHAPTER 2: LANDSCAPE DRIVERS AND PRESSURES ON THE MARY RIVER CATCHMENT 2.1 THE MARY CATCHMENT AND OVERVIEW ...... 18 2.2 LANDSCAPE DRIVERS ON WATER QUALITY………………………………………………………………………………………… 22 2.3 LANDSCAPE PRESSURES ON WATER QUALITY ...... 28

CHAPTER 3: WATER QUALITY IN THE MARY RIVER AND PROJECTIONS TO 2020 3.1 THE CURRENT CONDITION OF WATER QUALITY IN RELATION TO MANAGEMENT ACTION TARGETS ...... 41 3.1.1 Estuary and Freshwater concentration values...... 41 3.1.2 Development of local guideline concentration values as targets for on-ground delivery of River-care and Land-care management actions...... 42 3.1.3 Herbicide and Pesticide Risks In Fresh Waters ...... 46 3.1.4 Herbicide and Pesticide Risks In Marine Waters ...... 48 3.1.5 Groundwater Dependent Surface Water Systems in the Upper Mary Headwaters...... 49 3.1.6 Groundwater Dependent Surface Water Systems associated with coastal zone

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development...... 49 3.2 WATER QUALITY TRENDS IN RELATION TO RESOURCE CONDITION TARGETS .. 50 3.2.1 Nutrient trends in the Mary Catchment ...... 50 3.2.2 Physical-chemical trends in the Mary Catchment ...... 55 3.3 SEDIMENT AND NUTRIENT LOADS IN THE MARY CATCHMENT, AND PROJECTION OF LOADS WITH RESPECT TO MANAGEMENT OPTIONS...... 64 3.3.1 Improvements to catchment load delivery projected by landscape modelling. .... 64 3.3.2 Measured off site movement of sediment, nutrients, and herbicides from cane, forestry, mining, and main roads...... 65 3.3.3 Phosphorus measured in river sediment ...... 73 3.3.4 Best available projections of sediment and nutrient additions to receiving waters. 75 3.4 WATER QUALITY WITH RESPECT TO RESOURCE CONDITION TARGETS ...... 75 3.4.1 Hervey Bay and Great Sandy Straits...... 75 3.4.2 The Mary Estuary Management Unit ...... 76 3.4.3 The Lower Mary Management Unit ...... 78 3.4.4 The Upper Mary Management Unit ...... 78 3.5 WATER QUALITY WITH RESPECT TO ASPIRATIONAL TARGETS ...... 79

CHAPTER 4: ENVIRONMENTAL VALUES AND WATER QUALITY OBJECTIVES OF THE MARY RIVER AND MARINE RECEIVING WATERS 4.1 ENVIRONMENTAL VALUES ...... 81 4.2 WATER QUALITY OBJECTIVES ...... 82 4.3 ECOLOGICAL CHARACTER DESCRIPTION OF THE GREAT SANDY STRAIT 83 RAMSAR SITE......

CHAPTER 5: COORDINATED MANAGEMENT ACTIONS TO ACHIEVE TARGETS 5.1 WATER QUALITY TARGET SETTING ...... 86 5.2 MARINE RECEIVING WATERS: HERVEY BAY, GREAT SANDY STRAITS, MARY 88 ESTUARY MANAGEMENT AREA ...... 5.3 LOWER MARY MANAGEMENT AREA ...... 96 5.4 TINANA CREEK MANAGEMENT AREA...... 101 5.5 WESTERN MARY MANAGEMENT AREA ...... 106 5.6 UPPER MARY MANAGEMENT AREA ...... 111

CHAPTER 6: REASONABLE ASSURANCE STATEMENT 6.1 BACKGROUND ...... 118 6.1.1 Statement ...... 118 6.1.2 Knowledge of the Response of the System to Pollutant Loads ...... 119 6.1.3 Effectiveness of Proposed Interventions to achieve Load Reductions and improve Water Quality...... 119 6.1.4 Adoption of Proposed Interventions, in terms of Timing and Extent...... 121

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REFERENCES ...... 122

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ACRONYMS

BMRG Burnett Mary Regional Group for Natural Resource Management CCI Coastal Catchments Initiative COAG Council of Australian Governments DEW Department of Environment and Water (formerly Department of Environment and Heritage [DEH]) DLPG Department of Local Government and Planning DPIF Department of Primary Industries and Fisheries EPA Environmental Protection Agency EPP (W) Environmental Protection Policy – Water FBRSG Friends of the Burrum System Group (Inc) GPA Global Programme of Action for the Protection of the Marine Environment ICM Integrated Catchment Management IROL Interim Resource Operating Licence MRCCC Mary River Catchment Coordinating Committee NAPSWQ National Action Plan for Salinity and Water Quality NRM Natural Resource Management NRW Department of Natural Resources and Water (formerly Department of Natural Resources and Mines [DNRM]) NWQMS National Water Quality Management Strategy PMF Probable maximum flood RMP Riverine Management Planning WBWC Wide Bay Water Corporation WMU Waterway Management Units WQIP Water Quality Improvement Plan WQM Water Quality Management WRP Water Resource Plan

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CHAPTER 1:

BACKGROUND TO THE MARY WATER QUALITY IMPROVEMENT PLAN

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1.1 UNITED NATIONS GLOBAL PROGRAMME OF ACTION

Land-based sources of marine pollution are internationally recognised as a major environmental issue. The United Nations Environment Programme has initiated action through the Global Programme of Action for the Protection of the Marine Environment from Land-based Activities (the GPA). One hundred and eight governments, including Australia, have declared their commitment to protect and preserve the marine environment from adverse environmental impacts of land-based activities. As a result, the GPA was adopted in 1995.

In 1999, the 20th Session of the United Nations Environment Program Governing Council resolved to undertake the First Intergovernmental Review (IGR) of the GPA in 2001. Australia’s national report presented at this review was coordinated by Environment Australia, in collaboration with State and Territory governments. This report considered national coordination of efforts to address land-based sources of marine pollution, including the application of the following National policies and programs.

1.2 NATIONAL WATER QUALITY MANAGEMENT STRATEGY

Australia meets its GPA obligations through implementing policies, principles and industry guidelines of the National Water Quality Management Strategy (NWQMS). The NWQMS was introduced in 1992 by the Commonwealth, State and Territory Governments, in response to growing community concern about the condition of the nation's water bodies and the need to manage them in an ecologically sustainable way. The NWQMS is comprised of 21 guideline papers, the most significant and recent paper being the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000)1, which outlines a framework for water resource protection and management.

The Council of Australian Governments (COAG) Water Reform Framework incorporated the NWQMS in 1994. The COAG Water Reform Framework applies the NWQMS to coastal waters and wetlands, and the National Principles for the Provision of Water for Ecosystems, through the Framework for Marine and Estuarine Water Quality Protection

1 http://eee.ea.gov.au/water/quality/nwqms/index.html#quality

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1.3 FRAMEWORK FOR MARINE AND ESTUARINE WATER QUALITY PROTECTION

The Framework for Marine and Estuarine Water Quality Protection is a nationally consistent approach to protect the marine environment from land based pollution, therefore contributing to Australia’s obligations under the GPA. The Framework is based upon identifying and protecting the environmental values of water (detailed under the NWQMS). Key features of the Framework include identifying: • the environmental values of the coastal water; • the catchment that discharges to that coastal water; • the water quality issues and subsequent water quality objectives; • the maximum pollutant load to attain and maintain water quality objectives; • the total maximum load of pollutants associated with diffuse and point sources of pollution; • the river flow objectives needed to protect identified environmental values, having regard for matters such as natural low flows, flow variability, floodplain inundation, interactions with water quality and the maintenance of estuarine processes and habitats; • management measures, timelines and costs in implementing the plan; • the grounds for a "reasonable assurance" from jurisdictions; • security for investments to achieve the specified pollutant load reduction; and • environmental flow targets.

Priority coastal areas will be targeted for planning and subsequent funding. In the absence of an accredited water quality protection plan, interim water quality targets and pollution reduction strategies may be established to guide Commonwealth funding during plan development.

The Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC, 2000) underpins the application of this Framework. Terms used in the Framework, such as environmental value, water quality objective and monitoring and reporting have the same meaning as those in NWQMS documents. Water Quality Improvement Plans (WQIPs) developed using the Framework will identify management actions that would protect these values.

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1.4 THE WATER QUALITY IMPROVEMENT PLANNING PROCESS

The development of WQIPs broadly involves the following process: • capture current knowledge; • establish environmental values in consultation with key stakeholders; • develop water quality targets (concentration and load) that include and integrate management practice, catchment water quality and reef ecosystem targets; • identify appropriate management strategies to achieve water quality improvement targets (i.e. linking management action targets to resource condition targets); • develop an implementation plan, which includes modeling, monitoring and adaptive management strategies; • prepare a reasonable assurance statement that describes how plan implementation will achieve the plan's objectives.

Each WQIP is guided by a steering committee that includes representatives from the relevant regional NRM body, government agencies, industry groups, community groups and science providers. A broad group of representatives from the whole community is also invited to participate in the development process to ensure that local, indigenous, social, economic and scientific knowledge is brought together.

WQIPs are prepared in accordance with: • Australian Government's Framework for Marine and Estuarine Water Quality Protection 2 • Queensland Government's water quality management framework in the Environmental Protection (Water) Policy 1997 3 • (where appropriate) National Principles for the Provision of Water for ecosystems 4

This water quality improvement plan fits into the context of other plans relevant to the Mary catchment and or water quality. These are:

• The Great Barrier Reef Water Quality Protection Plan; • The Coastal Catchments Initiative; • The Great Barrier Reef Partnership; • National, State, Local Government and NRM Planning; • The Wide Bay Burnett Coastal Management Plan; • The Wide Bay Burnett Regional Plan; • The Great Sandy Region Management Plan; and • The Burnett Mary Regional Group (BMRG) NRM Plan “Country to Coast – a Healthy Sustainable Future”.

2 http://www.environment.gov.au/coasts/pollution/cci/framework/index.html 3 http://www.legislation.qld.gov.au/OQPChome.htm 4 http://www.environment.gov.au/water/publications/index.html#ecosystems

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1.5 THE GREAT BARRIER REEF WATER QUALITY PROTECTION PLAN (REEF PLAN)

In 2001 the Great Barrier Reef Ministerial Council authorised the development of a plan, to over a 10 year period reduce sediment and nutrient loads derived from the 26 catchments contributing to the Great Barrier Reef lagoon. This plan is known as the Reef Water Quality Protection Plan (Reef Plan). It is based on reviews that had identified the extent of water quality deterioration since European settlement, resulting from degradation of grazing landscapes, urban development, vegetation clearing, water use practices, removal of wetlands, and coastal developments on acid sulphate soils. There was evidence that these activities were affecting some inshore reefs, estuaries, and important near-shore areas. At the same time, the Plan was sensitive to the economic importance of industries within the coastal catchments including beef, sugar, horticulture, tourism, mining, and fishing industries.

In prioritising catchments for the RWQPP a risk assessment process that utilised the criteria of Bio-physical risk, Social risk, Development risk, and Risk to marine industries. The Reef Water Quality Protection Plan identifies the Mary Catchment as low in priority.

Reef Plan has 2 objectives: • reduce pollutant loads that enter the Great Barrier Reef Lagoon from diffuse sources, • rehabilitate and conserve areas of Reef Catchments that play a role in reducing/removing water borne pollutants.

Pollutant loads were selected as the targets for the plan because they measure the rate of pollutant delivery to receiving waters. Pollutant concentrations were also used for river health targets because they measure the pollutant available to aquatic organisms. These pollutant targets are to be incorporated into management plans being drawn up for the three large catchments that are part of the National Action Plan for Salinity and Water Quality (the Burdekin, Fitzroy and Burnett catchments). The Queensland government will draw up catchment management plans for the other 23 catchments.

A large component of Coastal Catchments Initiative, in terms of funding support towards the preparation of water quality improvement plans, is focused on priority catchments adjacent to the Great Barrier Reef.

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1.6 THE COASTAL CATCHMENTS INITIATIVE

The Australian Government, through the Coastal Catchments Initiative (CCI), is committed to improving the condition of Australia’s coastal waters through joint action with state and local governments. As a first step this will be achieved through the Water Quality Improvement Plans.

The Water Quality Improvement Plans will be consistent with existing government strategies, as described in sections 1.3 and 1.4. It will be necessary to take an adaptive management approach, drawing on the monitoring data and uptake of improved land management practices, whereby the WQIPs are regularly reviewed and modified.

Some of the parameters governing the development of WQIPs include: • Local ownership and leadership; • Cooperative action between the three levels of government; • Use of best available scientific knowledge; • Community involvement, including sectoral groups; • Contributions to regional objectives.

BMRG sought CCI funding to develop WQIPs for the Burnett and Mary. Because the Mary is a low priority catchment, it was not allocated CCI funding.

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1.7 THE REEF WATER QUALITY PARTNERSHIPS PROGRAMME

The Reef Water Quality Partnership was established to enhance coordination and collaboration between Australian and Queensland Government departments, and regional natural resource management (NRM) bodies. The Reef Water Quality Partnership supported the implementation of the Reef Plan and regional Water Quality Improvement Plans by providing a science foundation for setting targets, modelling, monitoring, and reporting.

A critical step in the Reef Plan was coordinating existing and planned water quality monitoring to inform targets. To support the Reef Plan, the Reef Water Quality Partnership: • coordinated and evaluated water quality monitoring activities; • implemented work plans and programs to deliver priority water quality activities; • supported improved land use planning and the adoption of sustainable production systems; • facilitated the development of water quality targets that link catchment management with the health of the Great Barrier Reef.

Organisations involved in the Reef Partnerships initiative

Australian Government departments involved include: • Department of the Environment and Water (DEW) • Department of Agriculture, Fisheries and Forestry (DAFF) • Great Barrier Reef Marine Park Authority (GBRMPA)

State Government departments include: • Department of the Premier and Cabinet (DPC) • Department of Natural Resources and Water (NR&W) • Department of Primary Industry and Fisheries (DPI&F) • Environmental Protection Agency (EPA)

Regional natural resource management bodies include: • Burdekin Dry Tropics Board • Burnett Mary Regional Group • Far North Queensland NRM • Fitzroy Basin Association • Mackay Whitsunday NRM

Framework for integration The framework for integration (Table 1.1) represents the breadth of activities of reef water quality stakeholders and how they may support delivery of the Reef Plan. This framework uses spatial

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and process linkages between catchment management, water quality and the health of the Reef to guide target setting, monitoring changes and reporting outcomes.

Table 1.1. How activities of reef water quality stakeholders may support delivery of the Reef Plan. The Reef Water Spatial linkages across environments Quality Partnership integration Water quality framework to Catchment management (sediments, nutrients & Reef health support for water quality management of contaminants) water quality.

Setting targets for Setting targets for Setting targets for catchment management water quality reef health that e.g. best management parameters across relate to water Targets practice adoption rates in scales from tributaries, quality e.g. high risk areas to improve sub-catchments and seagrass cover, water quality entering the end-of-catchments and coral recruitment. Reef. in the receiving waters.

Monitoring and Monitoring and Monitoring and modelling modelling the modelling catchment Modelling catchment management dynamics of the Adaptive water quality processes & practices and impacts eg health of the Reef management from the paddock to Monitoring best management practice lagoon in rivers and the marine impacts on water quality response to water environment. quality.

Evaluating and Evaluating and reporting change Evaluating and reporting reporting change in in the health of the Evaluation change in catchment management practice Reef and its & reporting management. across scales and component environments ecosystems and its drivers.

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1.8 NATIONAL, STATE, LOCAL GOVERNMENT AND NRM BODY PLANNING

Queensland’s river systems are governed by many National, State, Local Government and NRM Body planning processes. These processes include:

• Water Resource Planning (WRP) under the Water Act 2000. Lead agency – Department of Natural Resources and Water [NRW] • Riverine Management Planning (RMP). Lead agency – Department of Natural Resources and Water [NRW] • Water Quality Management (WQM). Lead agencies – Environmental Protection Agency (EPA) under the Environmental Protection Act 1994 and the Environmental Protection (Water) Policy 1997 and Amendment 2006 [EPP(W)] and Department of Natural Resources and Water [NRW] through Integrated Catchment Management [ICM] • Integrated Catchment Management (ICM) including Regional Natural Resource Management Strategies. Lead agency – Department of Natural Resources and Water [NRW] in association with Natural Resource Management Bodies e.g. Burnett Mary Regional Group [BMRG] • Regional Planning. Lead agency - Department of Local Government and Planning [DLGP] • State Coastal Management Plan and Regional Coastal Management Strategies. Lead agency - Environmental Protection Agency [EPA] • Wide Bay Burnett Coastal Management Plan. Lead agency - Environmental Protection Agency (EPA). “Plan presently in draft form and being considered by Queensland Government prior to release as a draft” • Council planning schemes under the Integrated Planning Act 1997. Lead agencies Department of Local Government and Planning [DLGP] and Councils • National Action Plan for Salinity and Water Quality (NAPSWQ). Lead agency – Department of Natural Resources and Water [NRW] along with Natural Resource Management Bodies such as BMRG • Regional Vegetation Management Plans. Lead agency – Department of Natural Resources and Water [NRW] • Fisheries Management Strategies. Lead agency – Department of Primary Industries and Fisheries [DPIF] • Water Use Plans. Lead agency – Department of Natural Resources and Water [NRW] and Interim Resource Operating Licences [IROLs] • Wide Bay-Burnett Regional Water Supply Strategy (announced by Hon Minister for Natural Resources 07.06.2007) • Land and Water Management Plans • Forestry Management Plans • Stormwater Management plans. Lead agency – Local Government and Environmental Protection Authority

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• Marine and Estuarine Water Quality Protection Plans. Lead agency - Department of Environment and Water [DEW] • Marine Park Plans • Global Plan of Action (GPA) for the protection of the marine environment from Land-based Activities • Framework for Marine and Estuarine Protection • National Water Quality Management Strategy (NWQMS). Lead agency - Council of Australian Governments (COAG) as part of their water reform framework • Great Barrier Reef Water Quality Protection Plan. Lead agencies - Queensland and Australian Governments • Coastal Catchments Initiative (CCI). Lead agency - Department of Environment and Water [DEW] • Water Quality Improvement Plans (WQIPs). Lead agencies - Regional NRM bodies and Local Governments consistent with the Framework for Marine and Estuarine Protection

Closer integration of the planning processes regarding water quality improvement planning is essential from two viewpoints: • processes need to address common goals, because effective outcomes are unlikely if planning processes work towards opposing goals; and • potential gains are to be made by reducing the duplication of effort between processes.

As part of the process of preparing a Water Resource Plan for the Mary Basin the Department of Natural Resources and Water and Environmental Protection Agency were seeking to develop a planning framework which more closely integrated the Water Resource Plan (WRP), Riverine Management Planning (RMP) and Water Quality Management (WQM).

1.8.1 The Wide Bay Burnett Coastal Management Plan

In 2007 the draft Wide Bay Burnett Coastal Management Plan stage was awaiting release by the Queensland Government. It considered water quality in detail, defined coastal districts, and the conservation and sustainability measures needed to protect these districts. However, the Queensland Government also reviewed and made public the Queensland State Coastal Management Plan in 2007. Following this process the Queensland Government decided not to release or develop further coastal management plans, but rather develop on overall process to manage coastal districts as defined in specific coastal management plans.

1.8.2 The Wide Bay Burnett Regional Plan

The Wide Bay Burnett Regional Plan 2007-2026 is the principal regional strategy for guiding growth and sustainability in the Wide Bay Burnett region. This plan has the following objective regarding water quality:

“to maintain water quality standards across the region which provide for maintenance of aquatic systems and services”

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and 2 policy principles:

• Regional water quality planning that is underpinned by reliable local knowledge • Improved community understanding of the interaction between human activities and water quality is fostered, and actions which contribute to improved local water quality are supported.

The Wide Bay Burnett Regional Plan 2007-2026 also gives following policy actions and assigns them to lead and collaboration agencies as follows:

• Regional water quality planning that is underpinned by reliable local knowledge

a Establish locally relevant environmental values and water quality objectives for regional waters in line with relevant water quality planning frameworks (EPA and BMRG associated with Industry Groups).

b Implement actions which: • broaden the spatial and temporal scope of regional water quality monitoring; • ensure the integrity of water quality data through standardised sampling, storage and analysis methods; • centralise data storage to develop a regional information asset; • review and refine water quality objectives for the catchments of the region (EPA and BMRG associated with NRW).

• Improved community understanding of the interaction between human activities and water quality is fostered and actions which contribute to improved local water quality are supported.

a Broaden community understanding of the importance of water quality protection and collective responsibility for improving water quality (BMRG associated with Local Government, EPA, NRW).

b Incorporate local water quality objectives into water resource planning, regional NRM planning, licensing of point discharges to water and review of water quality monitoring data (NRW, EPA, BMRG).

c Ensure water resource plans provide for adequate environmental flows of water to maintain in-stream and off-stream (overland flow and wetland) ecosystem processes (NRW associated with EPA, DPI & F).

d Implement and support programs that address identified threats to water quality, particularly: • diffuse (non-point) pollutant sources • inadequate water treatment infrastructure • ‘waste’ urban and industrial water • urban stormwater runoff

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• weeds such as cat’s claw creeper that threaten the integrity of riparian vegetation and thus bank stability during flooding events • dredge spoil (Local Government associated with BMRG, EPA, NRW, DPI&F).

e Ensure that new residential and industrial developments incorporate measures to reduce water demand, and sustainability manage waste and stormwater runoff, through policies in local government planning schemes (Local Government associated with EPA, NRW).

1.8.3. The Great Sandy Region Management Plan

The Great Sandy Region is composed of Fraser Island, the Cooloola Sandmass, Noosa North Shore and the waters of Hervey Bay and Great Sandy Strait. It covers about 840,000 hectares. The Great Sandy Region Management Plan 1994-2010 was prepared to protect natural, cultural and economic values of the Great Sandy Region. The plan envisages only a limited range of future, environmentally responsible tourist developments on Fraser Island.

Queensland Parks and Wildlife Service released a review of this plan in 2005. Between 1994 and 2005 the national park estate increased from 140,000ha to 220,000ha through the creation of the Great Sandy National Park that includes most of Cooloola and Fraser Island. Also in 1999 the Great Sandy Strait Ramsar Area was declared, because of its international importance for migratory shore birds.

In September 2006 two existing marine parks, Woongarra and Hervey Bay, were amalgamated with all other appropriate tidal areas (land and water) within the Great Sandy Region to form the Great Sandy Marine Park.

The Great Sandy Region Management Plan has a series of Management Strategies. Strategy 1 is concerned with Natural and Cultural Resource Development and considers water quality, integrated catchment management and scientific research all of interest to a Water Quality Improvement Plan. These strategies are: • Water Quality will be monitored and action taken to ensure water quality is maintained throughout the region, including marine areas • Integrated Catchment Management will be encouraged for river systems affecting the Great Sandy Region • Scientific Research focussing on species, sites and natural processes will be conducted to support management of natural and cultural resources within the Great Sandy Region.

Water quality has the desired outcome of:

“by 2010, to have water quality of all water bodies within the Great Sandy Region within limits necessary for maintenance of natural processes, biodiversity and ecological integrity”.

Designated proposed guidelines and actions are:

1. Water quality should meet minimum ANZECC (2001) guidelines for protecting aquatic ecosystems. All lakes and creeks where swimming occurs should meet ANZECC water

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quality guidelines for primary contact. Where water is extracted for drinking, it will meet ANZECC water quality guidelines for potable water (ANZECC guidelines for remote areas).

2. Water quality management strategies will be prepared for all key areas in the region. They are to include standards, indicators and a monitoring plan for estuarine areas, surface bodies and ground water supplies in each area. Standards can be set for specific sites or areas to meet ecological objectives that protect internationally and nationally environmentally significant values (e.g. World Heritage Areas) in the region where appropriate.

3. Studies aimed at understanding processes occurring in lakes will be undertaken and appropriate management strategies developed and implemented to maintain water quality within predetermined acceptable levels.

4. All water bodies and ambient water quality data will be monitored regularly and analysed to determine long-term water quality trends as a basis for adjusting motoring guidelines (e.g. frequency and level) and determining standards. Management strategies will be reviewed and adapted to ensure long-term water quality is maintained as determined by the Australian Water Resources Council.

5. Water quality studies will be done in co-operation with the statewide ambient water quality monitoring program being undertaken by EPA and DPI&F. The monitoring program needs to have flexibility to target new areas of concern, or areas of potential impact and attributes. Sites used for water quality monitoring will remain constant to the greatest possible extent to allow for long-term comparison of data with information stored on the statewide EPA database.

6. Nutrient inputs to lakes, streams and ground water will be minimised. Camping areas, toilets, waste disposal facilities and other facilities will be sited to minimise impact on water quality.

1.8.4 The Burnett Mary Regional Group for Natural Resource Management NRM Plan: Country to Coast – A Healthy Sustainable Future.

The Burnett Mary Regional Group for Natural Resource Management (BMRG) was established to achieve natural resource management arrangements in the Burnett and Mary Catchments, which have been identified by Federal and State Governments as catchments of concern. BMRG is responsible for developing and gaining collective agreement from relevant stakeholders on a NRM plan for the Burnett Mary Region. BMRGs NRM Plan “Country to Coast – a Healthy Sustainable Future” is divided into 6 action programs. One of these programs is the Water Quality and Equitable Use Program.

The aim of the BMRG Water Quality and Equitable Use Program is:

“to ensure water resources and associated ecosystems are managed, protected and harvested in an efficient, equitable and sustainable way for social and economic benefits whilst maintaining optimal environmental flows and ground water health now and for the future.”

The primary matters for target this action program addresses are: • M4 Nutrients in aquatic environments; • M5 Turbidity/suspended particulate matters in aquatic environments;

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• M6 Surface water salinity in freshwater aquatic environments; • M11 Critical assets identified and protected; • M12 Water allocation plans development and implication; • M13 Improved land and water management practices adopted.

The Water Quality and Equitable Use program has substantial links with matters for targets in other action programs: • M1 Land salinity; • M2 Soil condition; • M3 Inland aquatic ecosystem integrity; • M7 Estuarine coastal and marine habitats.

BMRG’s Water Resource Management Actions (WRIA-O) are concerned with setting end of catchment targets and developing Water Quality Improvement Plans to achieve long-term water quality improvements. This supports Reef Water Quality Protection Plan objectives to halt and reverse the long term decline of water quality in the Great Barrier Reef lagoon, and provides a framework for a more collaborative approach between the Australian Government, Queensland Government, Local Government and community organisations.

Setting end of catchment targets is to be achieved through both an assessment of baseline condition and trend, and modelling (e.g. Sednet). These actions support and/or implement a program for the development of environmental values (EVs) and water quality objectives (WQOs) to underpin WQIPs.

Activities include programs of on-ground support and incentives to involve regional stakeholders (Waterwatch, Rivercare, Coastcare, the Coastal Water Quality Alliance or similar) to identify and mitigate impact in water quality ‘hot spots’ and participate in both freshwater and marine monitoring. Activities also provide for a centralised data collection and reporting service and community awareness programs relating to offsite influences of land management practices on water quality.

Achieving optimal environmental flows through the development of Water Resource Plans (WRPs) and implementation of Resource Operation Plans (ROPs) throughout the Burnett/Mary region is the aim of BMRG management action (WR3H-J). The two main components of a healthy aquatic ecosystem are water quality and flow or quantity. Under the Water Act 2000 and water reform program, the water resource planning process is designed to plan for the allocation and sustainable management of water to meet Queensland’s future water needs, including the protection of natural ecosystems and security of supply to water users.

The setting of end of catchment targets, developing WQIPs to achieve long term improvements to water quality, optimal flows through development of water resource plans, and implementing resource operation plans are critical priorities in BMRGs NRM Plan “Country to Coast – a Healthy Sustainable Future”

High priority is also given in the BMRG plan to management actions (WRIP-S) that focuses on reducing diffuse and point source loads, and encouraging region-wide standards and adoption of Best Management Practice in Environmental Resource Assessment licence reviews. Diffuse and point sources of pollution are a major issue for receiving waters. They impact on local values such

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as fisheries and estuaries, and on a wider scale on sites of international significance such as Ramsar listed Great Sandy Straits and World Heritage Area Great Barrier Reef and Fraser Island. Work includes developing and implementing programs to encourage Best Management Practice by industry. This supports the Reef Water Quality Partnerships Program by reducing nutrients, sediments and agrochemicals entering the GBR lagoon.

Water Use Efficiency (WUE) initiatives are the focus of high priority management actions (WR3A- G). These activities promote and support water use efficiency across irrigation, urban, industrial and other users in partnership with industry and Local Government Authorities. Activities include a review of the efficiency of current water use systems, increasing public awareness of potential gains that can be made, and providing local industry contacts that can support these improvements.

A high priority management action (WR5A-D) addresses the effect of riparian condition on water quality, because riparian vegetation is essential for healthy waterways. Work has focussed on identifying sites and land management factors responsible for riparian zone instability, then prioritising devolved grants to landholders on the basis of returns for investment in environmental lift.

Important management action (WR2A-D) addresses current impacts of Acid Sulphate Soils (ASS) using community water quality networks. This management action is also is relevance to the Sustainable Use and the Coastal Marine Management Action Programs.

Priority issues influencing water quality in the Mary Catchment are listed in table 1.

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Table 1.2: Main Issues associated with the Mary Catchment.

Issue Relevant BMRG RCT/MAT Weed and animal pests: environmental and noxious weeds (eg giant rats tail, parthenium, cats claw LR3.1, LR3.2 creeper, Chinese elm, spread of Condamine couch) aquatic weeds (Cabomba sp, water hyacinth and Hygrophila sp) in particular. Support for co-operation between LGAs required Habitat restoration, removal of migration barriers, and other requirements to address needs of FB1.2, FB1.3 endangered Mary River cod, Mary River turtle and lung fish Significant issues related to water resources need to be addressed: WR3.2, WR3.1, • environmental flows FB1.3, WR4.1 Formatted: Indent: Left: 0 cm, • out of basin transfers Hanging: 0.95 cm, Bulleted + Level: 1 + Aligned at: 1 cm + Tab after: 1.5 • urban use, efficiency and demand cm + Indent at: 1.5 cm, Tab stops: • unregulated use of sub-artesian water Not at 1.5 cm • rural/industrial water demand, efficiency and reuse • ensuring adequate environmental flows over barrages (Mary River, Tinana Ck) to allow for spawning requirements of estuarine fish Implementation of the Mary River and Tributaries Rehabilitation Plan (MRCCC,2001) to address FR3.2, WR5.1 riparian habitat and streambank instability issues An overall poor water quality status in the channel zone of the estuary as documented by estuarine WR1.2, water quality monitoring and declining water quality in freshwater areas, particularly the upper WR5.1,FB3.2 Mary. Concerns re impacts of road run-off The estimated sediment, nitrogen and phosphorus inputs from the Mary catchment is significantly WR1.2 high. This is an issue for this catchment given the environmental, social and commercial values of the receiving waters (Hervey Bay and Great Sandy Straits) and its instream values. Predicted 60% increase of the population in the next 20 years with associated issues of environmental carrying capacity and social change The Mary catchment is most ‘at risk’ within the Burnett Mary region according to the RWQPP due to WR1.2 moderate to high risk for biophysical and economic impacts on marine industries and high risk for future development increasing pollution Need for extension services/assistance to implement actions (eg Property Management Plans, Environmental Management Systems, Best Management Practices) Important vegetation corridor linkages throughout the catchment need to be maintained TB1H Promotion of sustainable farm practices LR1, LR1.2 Documentation of biodiversity values TB2.1 Impacts of sand and gravel extraction on instream and downstream values LR2.2, FB2B Flood plain mapping and management Ecosystem simplification TB1.2

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CHAPTER 2

LANDSCAPE DRIVERS AND PRESSURES ON THE MARY RIVER CATCHMENT

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2.1 THE MARY CATCHMENT & OVERVIEW

The Mary is the second largest catchment with the Burnett Mary region (9181km²). The 310km long main-stem river rises in the Conondale Range, near Maleny in the Sunshine Coast hinterland, and flows into the Great Sandy Straits at River Heads. Major urban centres are Maleny, Kenilworth, Cooroy, Gympie, Kilkivan, and Tiaro, all of which contribute point source inputs into the river system. The Mary Catchment has several tributary creeks including Obi Obi, Yabba, Little Yabba, Six Mile, Amamoor, Kandanga, Tinana, Deep, Munna and Wide Bay Creeks.

The Mary Catchment is privileged with respect to its unique ecological assets. It is one of only two rivers in the world that hosts the Queensland Lungfish (Neoceradites forsterii), a living fossil related to the Devonian ancestral link to land based vertebrates. By contrast with African and South American lungfish species, N. forsterii has retained the physical appearance of the ancestral species implying that stabilising selection (Ridley, 2004) may be an important ecological process that links this species with its landscape. Also of interest is the Mary River Turtle (Elusor macrurus) that occurs only in this river. This turtle represents an ancient evolutionary lineage that has nearly disappeared from the Australia. Other noteworthy ecological assets are the RAMSAR listed wetlands of the Great Sandy Straits, which host migratory birds that travel from the Northern Hemisphere.

Economic activities in the Mary River Catchment include dairying, beef, forestry, fishing, horticulture, sugar, farm forestry, tourism, retail, manufacturing, agricultural, mining (sand and gravel extraction), building industries, small industry and cottage arts and craft. Gold mining continues to be important around Gympie. Tourism generates significant income for some Regional Councils. A brief history of development of the Mary Catchment can be found on http://mrccc.org.au/downloads/publications/MRCCC%20fact%20sheets/History%20of%20The%20 Mary%20River.pdf.

Collectively these industries put pressures on water quality in the Mary River, and its receiving waters (Great Sandy Straits, Hervey Bay). Sediment, total nitrogen and total phosphorus exports from the Mary catchment to the coastal receiving waters are estimated to be respectively (Kilotonne per year): 455, 1.541, 0.344 (DeRose et al., 2002). Since European settlement, relative erosion rates in some sections of the Western Mary have increased 2 to 7 fold, and 4 to more than 14 fold in the Upper Mary (Esslemont et al., 2006a). More recent estimates of sediment export, taking into account more detailed information on pasture cover across the Mary Catchment, give a similar estimate of sediment export to the coast (430-500 KT/Year) (Banti Fenti, NRW, pers comm.). This is significant to the environment, social and commercial values of its receiving waters (Hervey Bay, the Great Sandy Strait and Fraser Island) and in-stream values. There are likely to be further social consequences and environmental impacts from the predicted 60% increase in population growth in the next 20 years (http://www.dip.qld.gov.au/population- forecasting/population-projections.html).

For the purpose of describing the influences of landscape drivers on water quality, the Mary Catchment has been subdivided into landscape management units for this report (Figure 2.1.). This is to allow the customization of conceptual models to various parts of the catchment (Chapter 5).

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Figure 2.1: Landscape Management Units in the Mary Catchment

Catchment Statistics

Area of catchment: 9181km² Stream Length: 2079km Grazing: 4283km² Stream-flow: 2,300,000 ML Cropping: 98km² Rainfall: 700-2000mm/yr Irrigation (sugar, 217km² Regional Councils: 4 crops): Agricultural $200m gross Climate: Subtropical Production: State Forests: 1134km² Population: 91,700 people Pine Forests: Rare & Threatened 659km² 260 Species: Conservation Areas: 1818km² Landcare Groups: 8

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Shires within the catchment The Mary River Catchment supports about 440,370 people (Figure 2.2) living in 3 Regional Councils, some on the land but mostly in urban areas, rural subdivisions, and even outside the catchment (http://www.dip.qld.gov.au/docs/temp/population-update-13-230508.pdf). About 91,700 people live within the Mary Catchment itself (http://www.censusdata.abs.gov.au/ABSNavigation/prenav/PopularAreas?collection=census&period=2006). Population projections (medium series 2006-2031: http://www.dip.qld.gov.au/population- forecasting/population-projections.html) indicate strong growth in these Regional Councils (about 605,710 in 2021 and 714,470 in 2031).The Regional Councils are:

Fraser Coast Regional Council, Gympie Regional Council, Sunshine Coast Regional Council.

Small portions of the Somerset Regional Council and Moreton Bay Regional Council overlap the Mary River’s headwaters. The Somerset portion is largely forestry, and the Moreton Bay Portion largely dairy and rural residential subdivisions.

In 2007 The Queensland Government amalgamated 12 shires into the current Regional Councils. The 12 former shires were: Caboolture, Caloundra, Kilcoy, Maroochy, Noosa, Cooloola, Kilkivan, Woocoo, Tiaro, Maryborough, Biggenden, Hervey Bay.

Figure 2.2: Population density in the Mary Catchment.

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Water Infrastructure Development and Utilisation The Mary Catchment supplies water for local agriculture, urban and industrial water users as well as to urban users on the Sunshine Coast and within the catchment.

Water storages in the Mary Catchment include 4 dams (Cedar Pocket, Borumba, Lake McDonald, Baroon Pocket) with a collective capacity of 115.63 GL, five weirs with a collective capacity of 3.685 GL, and two barrages with a collective capacity of 16.47GL. These impoundments stabilise water supply for the two major irrigation developments in the catchment (Wigginton and Raine, 1999);

• The Mary Valley Irrigation Project (MVIP). This delivers about 10.7 GL per year to an irrigation area of 129.2 km2. The MVIP supplements flow through Yabba Creek and the Mary River, using Borumba Dam to supply water to users for irrigation, urban and industrial uses. • The Lower Mary Irrigation Area (LMIA). This delivers about 25.3 GL per year to an irrigation area of 191.1 km2. The LMIA is located between Maryborough and Tiaro. Water is supplied from the Mary River Barrage, Teddington Weir and Tinana Barrage for irrigation of sugar cane, improved pasture and horticulture.

Beyond these irrigation schemes, Baroon Pocket Dam provides about 2GL per year to irrigators and 36GL per year to urban users in Coulandra City and Maroochy Shire, and smaller allocations are drawn from Teddington Weir and along Deep Creek (Wigginton and Raine, 1999). Water supplies for towns within the Mary Catchment are obtained from local streams, usually from small weirs constructed to pond water to facilitate pumping. Un-supplemented water harvesting of natural flows from the Mary River’s tributaries occurs, and natural flows occasionally fail to meet dry season requirements for streams in the Western Catchments.

In a scoping study to evaluate opportunities for improving water use efficiency, Wigginton and Raine (1999) evaluated water use in the Mary Catchment. These authors identified the main distributions of regulated water were to the cane sector (which held 34% of allocations), the dairy sector (25%), local authorities (16%), and the beef sector (13%). Horticultural production (nuts, small crops, and fruit) collectively used less than 5% of water allocations. Wigginton and Raine (1999) identified that the greatest volumetric gains in managing water demand in the Mary Catchment could be achieved by efficiency gains in the dairy sector.

The Queensland Government announced on April 2006 its intention to build a large dam on the Mary River at Traveston Crossing. The government has stated that this dam is part of a water grid along the Queensland East Coast, which is required to drought proof water supplies for Brisbane and South-east Queensland. Up to that time, there had been no direct public notification or consultation. The only information available was that landholders in the dam footprint (approximately 900) would be notified. This announcement was greeted with considerable public opposition from within the Mary Basin.

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2.2 LANDSCAPE DRIVERS ON WATER QUALITY

Overview of the Receiving Waters of the Great Sandy Strait and Hervey Bay Estuarine and Marine wetland habitats depend on five components and processes that support ecosystem services (Mike Ronan, pers comm. Based on draft Ecological Character Description for Great Sandy Strait Ramsar site). These are:

1) Passageways at the extremities of the strait, which connect riverine, estuarine, and open water habitats. 2) The sheltering aspect North West of the Fraser Island. 3) High dunes that supply fresh and ground water westward into adjacent wetlands. 4) Estuarine and freshwater connectivity and flows, particularly from the Mary River; 5) Transport and deposition of sediments of marine and terrestrial origin, in a tidal estuary.

The extensive seagrass meadows of the Great Sandy Straits and Hervey Bay are one of the largest single seagrass resources on Australia’s East Coast (Lee Long et al., 1993). The Great Sandy marine ecosystem is underpinned by primary production of seagrass meadows (http://www.epa.qld.gov.au/nature_conservation/habitats/marine_habitats/seagrass/). Seagrass habitat is limited by turbidity and epiphytic algae overgrowing leaf surfaces (caused by increased nutrient bioavailability), which shades seagrass and prevent photosynthesis (Waycott et al., 2005).

The extent of seagrass cover varies. Some reports suggest that seagrasses have contracted in area because of major floods (e.g. Preen et. al., 2000). Campbell and McKenzie (2004) reported on post flood monitoring of the 1999 event, in Hervey Bay and the Great Sandy Strait, that recovery of deeper water seagrasses was limited by turbidity and associated high nutrient loads during a very active wet season (Figure 2.3). Some shallow water sub-tidal seagrass species did not recover. However reduced freshwater flows over the last decade have contributed to a marine transgression into the Burrum and Mary estuaries’. Local observation has noted seagrass recruitment in the lower Burrum estuary (Tim Thornton, Friends of the Burrum River System Group, pers. comm). Seagrass recruitment responds to changes in turbidity, nutrients, and salinity in Hervey Bay, Great Sandy Straits, and the Mary Estuary.

The Western region of Hervey Bay has a naturally occurring hypersaline zone characteristic of an inverse estuary (Ribbe, 2008), which is balanced by rainfall and river discharge. The variability of freshwater inputs is linked to changes in the hydrographic structure of the bay, which may influence the marine ecosystem and fisheries of the bay. This hydrographic structure involves high density saline water flowing along seabed contours out of the bay (towards the edge of the continental shelf), below an incoming layer of less dense, seawater of normal salinity. Mechanical energy from tides and waves are insufficient to disrupt the density stratification that develops from evaporation, temperature, and freshwater fluxes during the residence time of water in the basin between Fraser Island and the mainland (Ribbe, 2008).

The East Australian current is an important process for longshore transport of sediment along the continental shelf. Fraser Island is the northern extent of the South East Australian longshore sediment transport system, and the island deflects northerly transport of 500,000 cubic meters per year of sediment to the edge of the continental shelf as a “river of sand” (Boyd et al., 2004). This cascades off the edge of the continental shelf slightly north of Fraser Island, at about the same point that salinity density currents flow over the shelf (Boyd et al., 2004; Ribbe, 2008). In the protected bay north west of Fraser Island, estuarine muds and coastal barrier sands are deposited in a large tide delta between the tip of Fraser Island and Theodolite Creek (Boyd et al., 2004).

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Defined plume

Burrum River

1999 Flood Plume Mary River in Hervey Bay

Figure 2.3. Extent of a turbidity plume (orange line) from a large flood that entered Hervey Bay. The turbidity from this event extensively smothered seagrass beds (Preen et al., 2000).

Tidal Drivers of Water Quality

Tidal energy redistributes sediment within the Mary River estuary, which is a primary driver for the formation of mudflats, tidal channels, and distributary channels that cut through mangrove flats. Unlike the wave dominated estuaries of the Elliott, Burnett, Kolan and Baffle, the Mary Estuary is well protected from waves by Fraser Island, Big Woody Island, and the shallow flats of the Great Sandy Straits (Saintilan, 1996). Consequently the Mary River estuary has been classified as a tide dominated estuary, with three zones (Saintilan, 1996):

1) The marine zone that terminates slightly west of Brothers Island, effectively at the EPA sample site at 17.7km. This zone has a variety of geomorphic units that include a wide inter-tidal flat, rocky inter-tidal shores (outcrops of sedimentary rocks), mid channel islands (the Crab Islands, Brothers Island, and shoals), and tidal creeks that dissect the tidal flats that are stabilized by mangroves.

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2) The central zone of low energy where river discharge and tidal currents mix, which is marked by a sudden restriction in cross-sectional channel area. This zone includes all the EPA sample sites landward from 22.5km to the Mary River Barrage that was built in 1982 to prevent the intrusion of tidal saline water. This zone has one geomorphic unit of channel- fringing flats that are usually steeply sloping and colonized by bands of mangroves. Some flats have been eroded by flood discharges, leading to bank slumping, but there is also rapid aggradation of levee banks from overbank flows that have half buried fence posts on adjacent farmland (McNamara, 1984). There have been observations of bank erosion seaward of the barrage (McNamara, 1984). Tidal barrages prevent tidal energy from being dispersed further landward, and the consequence of tidal barrages on estuarine hydrography is increased tidal range, and decreased tidal flows, with distance from the mouth of the estuary as has been modelled for the Burnett River Barrage (Miller, 1985).

3) The river dominated zone, upstream of the Mary River Barrage. Before the Barrage was installed, the Mary River was tidal to an outcrop of rock bars just upstream of Tiaro, 80km from the mouth. This section of the estuary is now permanently freshwater.

It is important to note that the tide-dominated nature of the Mary Estuary means that it is naturally turbid because of tidal re-suspension and continuous movement of sediment (http://www.ozcoasts.org.au/conceptual_mods/geomorphic/tde/tde.jsp). Tidal heights were measured at the Urangan Storm Surge Gauging Station (station number 058009B) between July 1981 and December 2005 (Figure 2.4). Statistically significant tidal cycles occur at 111, 106, 66, 62, 56, 50, 36, 28, and 4 day periods. The average diurnal tidal range is 2.3m, with the maximum tidal range (3.8m) recorded on 9/3/2001. The highest recorded tide is 4.369m.

Tidal Range at Urangan 4 3.5 3 2.5 2 Metres 1.5 1 0.5 0 23/09/1994 19/06/1997 15/03/2000 10/12/2002 5/09/2005 Date

Figure 2.4: Tidal ranges measured at the Urangan Storm Surge Gauging Station.

Tidal cycles are an important driver of physical habitat in the geomorphic zones of the Mary Estuary, and the consequent influences on water quality as described in Chapter 3. Saintilan (1996) considered that unlike many sub-tropical estuaries along the South East Queensland coast that are mature, the Mary River estuary has an intermediate stage of development. Eventually

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extensive deltaic mangrove environments may connect Fraser Island with the mainland (Saintilan, 1996).

Geological and Soil Drivers of Water Quality The regional geology is summarized with respect to Landscape Management Units (Figure 2.1) used for this Water Quality Improvement Plan. To assist with the development of conceptual models, rock-types and soil families were grouped on the basis of their potential influence on downstream water quality (Esslemont et. al., 2006a). Rock-types/soil families that are statistically significant contributors to landscape variation are listed in tables 2.1 and 2.2 (Esslemont et. al., 2006a).

The rock-types are crystalline rocks (andesite, serpentinite, quartz-bearing intrusive rocks) that predominantly occur in the headwater sections, and sedimentary rocks the predominantly occur in the downstream sections.

Quartz- Sedimentary Sedimentary Metamorphic Landscape Andesite bearing Rock: Rock: Sedimentary serpentine Management Basement intrusive Cainozoic Cainozoic Rock basement Unit basement coastal terrestrial Upper Mary 6 6 16 0 8 34 Western Mary 13 4 27 0 10 38 Tinana Creek 1 0 0 0 32 56 Lower Mary 10 0 3 0 20 54 Mary Estuary 0 0 0 7 46 34 Table 2.1: Percent coverage of geological basement in the Water Quality Improvement Plan subsections.

Crystalline basement rocks (andesites, quartz-bearing intrusives) contribute to watershed function by the development of coarse sediments and river gravel that conduct groundwater into spring-fed and ephemeral streams. Denitrification processes occur during under-gravel flow. Quartz and feldspar grains contribute to loam soil structure, which assists with water infiltration into the soils of catchment headwaters. Kaolin clays derived from these crystalline rocks have an anion exchange capacity that binds phosphorus, and may have sodic properties that make them prone to erosion and easily dispersed by wetting.

Serpentine basement rocks are soft and easily eroded, so are down-cut by mechanical erosion that contributes to landscape topography. These rocks are prone to chemical weathering, and their calcium and magnesium rich composition directly influences the magnesium hardness, alkalinity, and bicarbonate buffering properties of water in the Mary Catchment.

Sedimentary basement rocks have aquifer potential. Some geologically young basement rocks that were deposited in the coastal zone during the Cainozoic, and include estuarine and shallow marine sediments, may host acid sulfate soils.

Soils of the Mary Catchment that have medium to high erosion hazard are sodosols, tenosols, kandosols, and dermosols. Tenosols on shallowly sloping hills tend to be left as native vegetation, so usually don’t contribute significantly to sediment and nutrient loads in streams. However if disturbed, these soils can contribute substantially to nutrient loads in streams. Hydrosols have moderate to high erosion hazard, but occur on low points in the landscape so tend to remain in- situ. Ferrosols have low erosion hazard, but are often tilled for agriculture that greatly increases their erosion risk.

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Landscape Management Unit Dermosols Ferrosols Hydrosols Kandosols Sodosols Tenosols Upper Mary 19 18 0 4 3 27 Western Mary 22 8 0 0 17 42 Lower Mary 12 1 3 9 30 17 Tinana Creek 8 2 4 48 17 8 Mary Estuary 11 0 34 8 27 0 Table 2.2: Percent abundance of soil families in the Water Quality Improvement Plan subsections.

Soils with high salinity hazard include sodosols, and hydrosols. Because hydrosols act as sumps they can contain abundant salt, and are often associated with salinity in coastal areas. Ferrosols carry salinized groundwater because they function as groundwater recharge zones, and salinity outbreaks can occur at the edges of ferrosols.

Soils that can contribute to nutrient leaching include dermosols, and ferrosols due to the same recharge properties that carry salts. Hydrosols are sumps that accumulate nutrients. Low nutrient loads are normally expected from kandosols, but if fertilizers are applied they have high nutrient leaching risk.

The Mary River Valley contains fertile alluvial soils that deserve mention because of their agricultural importance, their vulnerability to bank erosion, and because they are important floodplain sinks for phosphorus rich clays carried downstream from the fertile Maleny Basalts. These are geologically young soils deposited during floods under the control of three major constrictions:

• upstream of Kenilworth, between Camboon Bridge and Walli Creek confluence, where the river flows from a broad valley developed over the Neurum Tonalite to a narrower valley cutting through the more resistant Amamoor Beds. • downstream of Kenilworth, at Moy Pocket, where the river course is confined by the Kenilworth Bluffs. • downstream of Gympie, at Fishermans Pocket, where the river flows into a gorge through the Myrtle Creek Sandstone. This constriction affects hydraulic conditions in the vicinity of Gympie.

Bridges et al., 1990 mapped Mary River valley soils between Gympie and Kenilworth. They mapped an alluvial bench within the present high flow channel as well as 3 main terrace levels with distinctly different suites of soils. • alluvial benches within high flow channel (1-7m above bed level) • low terrace/present floodplain (8-12m above bed level) • intermediate terrace (15-20m above bed level) • high terrace

Alluvial soils associated with the ancestral Mary River were deposited during the late Pliocene and Pliestocene along the present river course; a broad, older outer valley, within which is a narrow, younger inner valley (Bridges et al., 1990). The older valley contains a high terrace cut into country rock, hosting alluvial sediments with sesquioxide properties that have been lateritized. There are

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also intermediate alluvial terraces featuring shallow back-channel depressions, and small levees along the back channels. These intermediate terraces are overtopped by floods every 15 years, and are slowly accumulating topsoil within the confines of the high terrace. The younger valley was possibly initiated during the Pliestocene, by downcutting associated with low sea levels. This river valley has subsequently been filled with some 50m of alluvia to form the present riverbed (Bridges et al., 1990). This valley is bounded by low floodplain terraces, levee banks, and in places narrow benches adjacent to the current stream bed formed by flood alluvium or bank slumping. These levees are overtopped by floods every 10 years (Bridges et al., 1990).

Climate Controls on Water Quality The coastal and southern ranges of the Mary Catchment have a moist sub-tropical climate, and the Western Mary Management Unit is dry sub-tropical. Mean annual rainfall ranges from around 2,000mm in the headwaters of the Upper Mary Management Unit, to less than 800mm in the Western Mary Management Unit. The Mary Catchment receives high intensity summer rains associated with tropical lows and cyclones that promote stormwater activity. The catchment also receives southern winter rainfall patterns of lesser magnitude. Rainfall varies considerably from year to year.

River flow is the key natural driver of fluvial geomorphic processes within the Mary catchment, because it is the source of kinetic energy that determines channel structure. Flow also affects riparian and aquatic vegetation, which in turn has geomorphic implications by affecting hydraulic roughness and the resistance to erosion of river beds and banks.

The oldest continuously recording stream gauge in the lower Mary has recorded between 122,000 and 4,665,000ML per year. The contribution of discharge from catchment streams is listed in table 2.3.

Stream Catchment Area (square km) Mean Annual Discharge (ML) Mary River 9595 2,309,000 Tinana Creek 1310 313,000 Munna Creek 1475 296,000 Wide Bay Creek 775 86,000 Obi Obi Creek 202 156,000 Table 2.3: Estimates of mean annual discharge for major catchment streams Topographic Controls on River and Reach structures that influence Water Quality.

There are significant topographic differences between the east- and west-bank tributaries of the Mary River, influenced by the underlying geology and weathering regimes described in the previous 2 sections. The Upper Mary and the Western Mary landscape management units have tributaries characterised by high energy flows, particularly down the mountain valleys. In the Upper Mary, Obi Obi Creek is a distinctive, high relief catchment falling steeply from a plateau of Tertiary volcanic rock. Six Mile Creek and Deep Creek contain younger rocks with lower relief.

The upper reaches are the steepest (Table 2.4) and the Mary River gradient shows a general downstream decrease to below Glastonbury Creek, where the gradient becomes steeper again before flattening out in the tidal area. Before construction of the Mary Barrage, the natural tidal limit was a rock bar upstream of Tiaro at AMTD 84km.

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Landscape Management Average topography Minimum topography Relief contrast Units (m above sea level) (m above sea level) (metres) Upper Mary Management 261 28 835 Unit Lower Mary Management 76 10 477 Unit Munna Creek 172 17 692 Wide Bay Creek 222 40 662 Widgee, Glastonbury, Pig 187 32 673 and Calico Creeks Tinana Management Unit 66 10 473 Mary Estuary Management 16 0 81 Unit Table 2.4: Topographic features of the Water Quality Improvement Plan subsections.

The river’s capacity to transport sediment via its discharge potential, coupled with the catchment’s capacity to supply sediment to the river, change at different nodes of the river. The resultant fluvial geomorphology has been described as 47 definable river reaches (http://mrccc.org.au/downloads/publications/Mary%20River%20&%20tributaries%20Rehabilitation %20Plan/Figure%205.5%20Reach%20Prioritisation%20A4%20map.pdf), each with a distinctive “Riverstyle” structure based on valley confinement, bed-form, riparian and bank structure (http://mrccc.org.au/downloads/publications/Mary%20River%20&%20tributaries%20Rehabilitation %20Plan/Appendix%201%20-%20Reach%20Summary%20Sheets.pdf). To have a workable spatial framework it is useful to consider these reaches in the context of landscape patches (e.g. Landscape Management Units for the purpose of this report) that exert definable landscape drivers on sediment supply and discharge.

Geomorphic variables at the management section scale (upstream catchment area, site elevation) influence variables (discharge, water chemistry) that more directly influence physical habitats at the sub-reach scale. Mackay et. al. (2003) showed that decreased site elevation in streams that drain the Western Mary and Upper Mary Management Units’ varied directly with increased water velocity and discharge, and inversely with the “flashiness” of stream flow. Water chemistry in these streams also varied with site elevation (Mackay et. al., 2003). The topographic controls on stream hydrology and water chemistry across the western subsections of the Mary Catchment underpin the community structure of submersed macrophytes (specifically different abundances of Myriophyllum verrucosm, Vallisnera nana and Potamogeton crispus).

2.3 LANDSCAPE PRESSURES ON WATER QUALITY

Water Infrastructure Pressures on Water Quality

Water storages are essential for the economic viability of the region, but altered flow regimes affect riverine hydrology putting pressure on riverine flora (e.g aquatic plant community structures, as described by Mackay et al., 2003) and fauna (e.g. fish community structures, as described by Kennard et al., 1998).

Un-supplemented extraction, for example in the ephemeral (flashy) streams draining the Western Mary headwaters, is highly relevant to habitat conditions because hydraulic habitats are changed by unnatural reductions of base-flow, or cessation of base-flow if pools are pumped dry. These pools are critical refuge habitats for water dependent biota during extended dry periods. Pump pool excavation accompanies un-supplemented extraction in some streams, causing local changes to the physical structure of the channel and potentially increased sediment mobility.

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Impoundments create still-water habitats where floating aquatic weeds transported from upstream accumulate. Water hyacinth (Eichornia crassipes) and Salvinia (Salvinia molesta) have been recorded as problems above the Maryborough Barrage (Steve Burgess, MRCCC; pers. comm.). The barrage has a functioning vertical slot fish ladder design (Stuart and Berghuis, 2002), but there is opinion that several fish species cannot use it because of the influence of the floating weed mat (Mary River Study Task Force, 1992). Siltation and bank erosion are also a problem resulting from altered hydrology resulting from impoundments (McNamara, 1984). Impoundments are also known to promote bank erosion in regulated rivers (Tilleard et. al., 1994), particularly when soils are erodable and easily undercut by the uniform water levels usually associated with weir levels and supplementary flow releases.

Flow strategies being utilised in 1998 by managers of storages included: • Borumba Dam passes on 20th Percentile flows. • There were no specific releases at the Maryborough Barrage. It generally overflows 300 out of 365 days which equates to 2.5Million ML/yr. • Supplementary flows from Lake Baroon and Borumba Dam to service downstream irrigators. • no specific action or strategies exist for the Weirs in Tinana Creek and Cedar Pocket.

The proposed Traveston Dam will substantially influence the flow regime of the Mary River. At the time of this report there was no publicly available information about the resource operations of this dam with respect to environmental flows. Those opposing the building of the dam believe that the dam will: • Adversely impact on environmental flows along the Mary River, a system which discharges into the Great Sandy World Heritage area and the Great Sandy Straits declared RAMSAR wetland area. • Adversely impact upon the Hervey Bay marine area and Fraser Island, a World Heritage area. • Destroy habitat for rare and threatened species (Australian Lungfish, Mary River turtle). • Destroy 76 km2 of prime agricultural, income producing farmland close to major population centres and force the relocation of businesses and families from the Mary Valley. Current Land Use Land-uses are summarised with respect to landscape management units (Table 2.5, Figure 2.5). Grazing predominates in the drier Western Mary Management Unit, and utilises 42% of the land area of the Mary catchment. High rainfall areas to the south and east host the majority of residential development, horticulture, and intensive livestock. Forestry and nature conservation, each of which occupies 18% of the catchment, are the second largest land uses, with intensive anthropogenic uses (residential, manufacturing, services, waste treatment, transport, and services) occupying 13% of the catchment area. Intensive livestock and irrigated cropping each occupy 3% of the Mary catchment area.

Johnston and Wylie (1984) revealed a relationship associating tree clearing with stream salinity and the occurrence of dieback in riparian Eucalyptus and Casuarina species. Bevege and Simpson (1981, cited in Lamb 1986) found that native vegetation cleared from poorly drained humic gleys led to the death of young roots caused by salinity associated with rising water tables.

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Intensive Landscape anthropogeni Intensive Management Unit c livestock Grazing Marsh/wetland Aquatic Upper Mary 17 6 31 0 1 Western Mary 6 2 68 0 1 Lower Mary 19 3 44 0 2 Tinana Creek 5 1 15 0 1 Estuary 20 0 31 5 3 Landscape Vegetable & Irrigated Nature Management Unit fruit crops cropping conservation Pine forestry Forestry Upper Mary 1 0 24 4 15 Western Mary 0 2 14 2 6 Lower Mary 1 3 7 0 21 Tinana Creek 2 5 22 39 10 Estuary 0 10 23 6 0 Table 2.5: Landuse distribution among management units in the Mary Catchment.

Forests cleared from steep slopes greatly increase the potential for mass movement. Landslides occur particularly in the Dagun, Cedar Pocket and Beenham Valley localities. A slip directly above the Cedar Pocket Dam site contributed significant amounts of sediment to the waterway. Ciesiolka et al., (1995) demonstrated the hazards associated with poor land management practices by pineapple farms on steep slopes in the middle catchment. They showed that soil erosion by rilling in experimental plots increased four times when the row length was increased from 12 to 22m on slopes of 38%. During the wet 1998/99 experimental period, this was a soil loss of 178 tonnes per ha. The potential for these sediments to be attenuated and enter creeks and rivers will depend on their proximity to the waterway and the capacity of the landscape to retain sediments on alluvial fans and floodplains.

Plant detritus and dissolved organic matter (black-water) enters tributaries of the Mary River, where it rots in the water column and consumes dissolved oxygen and soluble nutrients as a function of bacterial activity. The type and amount of carbon washed into waterways controls the rate of oxygen drawdown during black-water events that cause fish kills. Because the carbon from pasture grassland and sugar-cane is more immediately bio-available than carbon from eucalyptus forest, parts of the agricultural landscape potentially “fast feed” rivers with carbon, particularly in ephemeral rivers or regulated sections of river when un- seasonal flows are used to satisfy downstream demand. This may leads to pressures related to excessive decomposition rates in the water column and faster nutrient turnover (Esslemont et al., 2007).

Concentrated human additions of nutrients into the Mary also come from treated sewage, particularly from 2 main point sources (Maryborough STP at Aubinville, Gympie STP). There are

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some inputs from other STP’s, and also the risk of land based disposal ponds overflowing during high rainfall events (Table 2.6).

Table 2.6 Sewage Management in the Mary WQIP region. 2007-08 N 2007-08 in 2007-08 P in Management Total STP Lat Long discharge discharge Unit Discharge (metric (metric tons) (ML) tons) Estuary Aubinville -25.5189 152.7247 2089 88 * 19 * Lower Mary Gympie -26.1830 152.6670 1321 24** 15** Western Mary Kilkivan -26.0830 152.2500 922 - - Western Mary Goomeri -26.1769 152.0684 748 - - Great Sandy Cooloola 294 4** 4.9** Straits Cove -25.9942 152.9976 Great Sandy 375 3.5** 4.8** Straits Tin Can Bay -25.9196 152.9896 Great Sandy Rainbow 118 1.9** 2.4** Straits Beach -25.8664 153.0678 Lower Mary Imbil -26.4346 152.6850 0.598 0.015** 0.023** Upper Mary Cooroy -26.4170 152.9170 Upper Mary Kenilworth -26.5820 152.7390 Upper Mary Maleny -26.7670 158.8500 Number of Approximate Management Treatment Connected STP sewer number of Unit % land level Population disposal connections Septics Estuary Aubinville 44 Secondary 9,549 27,211 2,000 Lower Mary Gympie 13 Secondary 6,703 18,700 ? Western Mary Kilkivan 0 Primary 242 580 ? Western Mary Goomeri 71 Primary 346 830 ? Great Sandy Cooloola 2,075 3,735 Straits Cove 0 Primary ? Great Sandy 1,382 3,317 Straits Tin Can Bay 0 Primary ? Great Sandy Rainbow 1,192 2,384 Straits Beach 0 Primary ? Lower Mary Imbil 100 Secondary 240 ? Upper Mary Cooroy Upper Mary Kenilworth Upper Mary Maleny * Kjeldahl digestion (values will potentially be higher than for per-sulfate digestion). ** Persulfate digestion

Urban landscapes have direct influences on fringing reefs and near-shore habitats of the Marine receiving waters of Hervey Bay, as discharges from the Burrum (Eli Creek, Tuan Tuan Creek, Pulgul Creek) and Mary catchments. Adverse influences include:

• Activation of acid sulfate soils, resulting from cleared land and constructed lakes (e.g. Eli Creek in Hervey Bay). Acid sulfate risk areas are shown in figure 2.9. • More intense stormwater delivery onto fringing reefs (e.g. Tuan Tuan Creek in Hervey Bay). This has resulted from clearing of wetlands, installation of drains, and channelisation of stormwater.

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• Less interception of nutrients entering streams via groundwater seeps. This has resulted from loss of riparian buffer strips. • High nutrient loads resulting from sewage effluent, through septic tank leachate or STP discharges. • Environmental hazards resulting from industrial effluent (e.g. Pulgul Creek).

Figure 2.5: Landuses in the Mary Catchment.

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HERBICIDE AND PESTICIDE PRESSURES ON WATER QUALITY There are threshold concentrations with respect to herbicides and pesticides in waterways, which need to be observed to maintain water quality consistent with environmental values and water quality objectives (Queensland Environmental Protection Agency, 2004) or the environmental guidelines (ANZECC and ARMCANZ, 2000; Queensland Environmental Protection Agency 2006; Great Barrier Reef Marine Park Authority, 2008).

Several landuses apply herbicides and pesticides, and are possible sources for off-site movement of these compounds. These landuses include cropping, forestry, residential, services, transport, and harbours. Several local studies have investigated the risk of herbicides and pesticides moving from cane farms (Simpson at. al., 2000; Simpson et al., 2001; Stork et al., 2006). Simpson et al., 2000 measured the days after application for 50% of the herbicide to be dissipated by ultra-violet or microbial breakdown (DT50), which is the period when there is a risk of rainfall events mobilising herbicides into waterways. Most risk periods were 0.5 to 3 weeks after application (Simpson et al., 2001), varying with season, soil type and farming practice (Table 2.7). The dissipation rate of atrazine varies between 1 day and 27.5 days (under very dry conditions), with a median period of 3.5 days in surface soil. Diuron is relatively persistent, with DT50’s ranging between 6.5 - >250 days, with the average dissipation rate on agricultural soils found in the Lower Mary Irrigation Area being 12 days (Simpson et al., 2001).

Atrazine Diuron Ametryn Trifluralin Chlorpyrifos 2,4D Yellow chromosol Spring ------Summer 2.5 13 4 5 - - Grey kandosol Spring 13 - - - - - Summer 3 6.5-15.5 3.5 - - - Redoxic Hydrosol Spring 27.5 - - - 4 1.8 Summer 2.5 - 2 22.5 - - Data after Simpson et al., (2000). - signifies that no data were collected.

Table 2.7: Dissipation Rates (DT50's in days) for pesticides in surface (<2.5cm deep) soils.

Stork et al., (2006) measured runoff of diuron and its metabolic breakdown products over two rainfall events (each were about 50mm) from a sugarcane farm. Results were 7g/ha for diuron, 46 g/ha for 3,4-dichloromethylphenylurea (DCMPU), and 1 g/ha for 3,4-dichlorophenylurea (DCPU). In the surface sediments of a stream, Stork et al., (2006) measured about 99 g/ha for diuron, 132 g/ha for DCMPU and 23 g/ha for DCPU. Based on these observations, these authors contended that diuron and its breakdown products are accumulating in some waterways.

Recent studies have detected low herbicide concentrations in Tinana Creek, Lower Mary River, the Mary River Estuary, and the marine environments of Hervey Bay and the Great Sandy Straits (McMahon et al., 2005; Burnett Mary Regional Group, unpublished data). McMahon et al., (2005) identified that surface water concentrations of diuron, atrazine, simazine, tebuthiuron, and ametryn were higher during moderate flows than during low river flows.

PRESSURES RELATED TO SEDIMENT DELIVERY TO THE MARY RIVER

Pressures related to sediment processes include habitat alteration such as bank erosion and aggradation of stream beds in the Mary River (Johnson, 1997), and smothering of seagrass habitat in Hervey Bay (discussed in section 2.2)

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Long term records of total suspended sediments and discharge, measured by Queensland Department of Natural Resources and Water (NRW) gauges’, were used to very roughly compare sediment loads at different parts of the catchment. It is important to note that suspended sediment concentrations were not measured for all major runoff events, so this procedure cannot calculate true loads. It provides an estimate, which may be an underestimate because of lack of data.

Because apparent sedimentation rates vary as a function of time (Schlager et al., 1998), data of a consistent period from each gauge (1982-2002) and a standardised time unit (weekly loads) were represented. Calculations were done by the inter-sample mean concentration procedure, using software developed by the Queensland EPA (Marsh et al, 2006). Gauges used were Miva (NRW Gauge 138001A) to represent the Lower Mary Management Unit, Marodian (NRW Gauge 138004A) to represent Munna Creek (a creek in the Western Mary Management Unit), Bauple East (NRW Gauge 138903A) in the Tinana Creek Management Unit, and Dagun Pocket (NRW Gauge 138109A) in the Upper Mary Management Unit. Long term load calculations are shown in Figure 2.6. 800000 Miva (NRW Gauge 131001A) Average annual load (1982-2002) transported from the 4755km2 upstream area 700000 = 0.24 T/Ha/year 600000 Average annual load = 112 Kilotons

500000 400000

(Tons) 300000

Sediment Loads 200000 100000

0 11/06/1968 2/12/1973 25/05/1979 14/11/1984 7/05/1990 28/10/1995 19/04/2001 10/10/2006 Time (weekly time steps)

140000 Dagun (NRW Gauge 138109A) Average annual load (1982-2002) transported from the 2097km2 upstream 120000 area = 0.15 T/Ha/year 100000 Average annual load = 31.6 Kilotons

80000

(Tons) 60000

Sediment load 40000

20000

0 11/06/1968 2/12/1973 25/05/1979 14/11/1984 7/05/1990 28/10/1995 19/04/2001 10/10/2006

Time (weekly time steps)

Figure 2.6. Projected suspended sediment loads calculated from existing discharge and sediment records from the Mary River.

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Marodian (NRW Gauge 138004A) 12000 Average annual load (1982-2002) transported from the 990km2 upstream area = 0.021 T/Ha/year 10000 Average annual load = 2.05 Kilotons

8000

6000 (Tons) 4000 Sediment Load 2000

0 11/06/1968 2/12/1973 25/05/1979 14/11/1984 7/05/1990 28/10/1995 19/04/2001 10/10/2006 Time (weekly time steps)

Bauple East (NRW Gauge 138903A) 12000 Average annual load (1982-2002) tranported from the 783km2 upstream area = 0.03 T/Ha/year 10000 Average annual load = 2.23 Kilotons 8000

6000 (Tons) 4000 Sediment Load

2000

0

11/06/1968 2/12/1973 25/05/1979 14/11/1984 7/05/1990 28/10/1995 19/04/2001 10/10/2006

Time (weekly time steps)

Figure 2.6 (continued). Projected suspended sediment loads calculated from existing discharge and sediment records from the Mary River.

Because of the gaps in existing records of sediment loads and available landscape information, projections modelled by SedNet and other predictive models provide practical estimates of sediment and nutrient mobilisation through a catchment. Sednet modelling identified sections of the Mary Catchment that potentially deliver the greatest sediment load to the river, due to predisposing landscape characteristics of topography, soils, landscape cover and rainfall intensity (Esslemont et al., 2006a). The Upper Mary Management Unit has the greatest potential for sediment delivery to the river network. (Figure 2.7).

Several projects have commenced in the Mary River to address sediment delivery to the river (Mary River Catchment Coordinating Committee’s Rivercare project, Grazing Land Management project). Projected improvements resulting from these projects were modeled by SedNet (Esslemont et al., 2006b), and projections are discussed in chapter 3 of this report.

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Figure 2.7. SedNet Modelled Loads (T/ha/year) generated from the landscape (left map), delivered to the stream system (centre map), and delivered to the coast (right map). The modelling and maps were done by B. Fentie, Queensland Natural Resources and Water.

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SALINITY HAZARD

Salinity pressures result from land-uses that cause groundwater tables to rise to the soil surface, carrying salt into streams via groundwater seeps. This in turn limits vegetative cover where salinity scalds become established, and bare ground contributes to landscape erosion. High salinity hazard areas in the Tinana Creek Management Unit are mostly under forest where deep-rooted vegetation under eucalyptus and pine stands are maintained, avoiding the risk of rising groundwater tables. However there is a risk of salinization in medium salinity hazard areas where there is clear-felling, or where irrigation practices bring groundwater to the surface. Examples include land under irrigated cropping, agriculture, and grazing near Maryborough (the Mary Estuary Section), and under cropping near Gympie (the Lower Mary Section). If irrigation is allowed to percolate into the groundwater table of catena landscapes, salinity outbreaks can occur down-slope via groundwater seeps into drainages. Wastewater derived from some sewage can carry residual salt from the treatment process so, depending on irrigation practices, wastewater reuse carries a risk of localised salinity problems.

Salinity hazard (Figure 2.8) is summarised in the Landscape Management Units used in this report (Table 2.8).

Low - Medium Medium Medium - High High Landscape Low Salinity Salinity Salinity Salinity Salinity Management Unit Hazard Hazard Hazard Hazard Hazard Upper Mary 44 21 21 11 2 Western Mary 31 21 33 13 2 Lower Mary 10 10 36 37 8 Tinana Creek 4 2 17 50 26 Mary Estuary 2 1 19 47 19 Table 2.8: Salinity hazard coverage (% of the management section) within Water Quality Improvement Plan subsections.

There are 6 water types with respect to salt composition in the Mary Catchment (Lee Young, 1994), and each Landscape Management Unit has a distinctive combination of sodium chloride, calcium sulfate, and magnesium bicarbonate salts in surface water streams. Lee Young highlighted the influence of geology and other landscape controls on salt composition, and importantly on the relatively high conductivity waters (924 - 1217 µS/cm at 25oC) rich in magnesium and calcium bicarbonate in the Western Mary. These waters are unsuitable for irrigating salt intolerant crops, and have limited suitability for human consumption, but the water can be used to water stock. These landscape drivers mean that there is a need to address salinity hazard in the Western Mary Management Unit, to maintain the nominated environmental values for these waters (chapter 4). Hard waters also occur in the Upper Mary section, sourced from Kandanga Creek (393 - 404 µS/cm at 25oC), but these waters are suitable for all purposes because of lower salinity. The Tinana section has low salinity surface water dominated by sodium chloride (340 µS/cm at 25oC). The Lower Mary section also has relatively low salinity water (393 µS/cm at 25oC) of mixed composition.

Possibly a little unusually, the marine receiving waters of Hervey Bay and the Great Sandy Straits are also a salinity hazard zone, because the evaporation in the basin between Fraser Island and the mainland results in periodic hyper-salinity (Ribbe, 2008). Hyper-saline density currents exit Hervey Bay along seabed contours, eventually flowing off the edge of the continental shelf (Ribbe, 2008). Water demands associated with high population growth have led to consideration of desalination. Desalination carries the risk of adverse ecological outcomes, because hyper-saline

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water cannot be disposed of in this estuary without risk (or at least careful consideration of where outlet pipes are placed with respect to salinity driven circulation processes, to circumvent this risk). The risks of desalination plants are well known (Einav, et al., 2002), and include groundwater contamination when pipelines carrying seawater or brine are laid above an aquifer (because these pipes invariably burst), salinity plumes in the vicinity of the discharge pipe (which requires dispersive wave action to dissipate the brines), and the actual placement of discharge pipes in sensitive marine communities such as the Great Sandy Straits Marine Park.

Figure 2.8: Salinity Hazard in the Mary Catchment.

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Acid Sulfate Soils

Acid sulfate soils can potentially occur in marine sediments deposited up to 5 meters above the present sea-level in the Mary Estuary (Figure 2.9), and more likely less than 3 metres a.s.l. because of the stability of the Queensland shoreline during the Holocene (Ward, Little and Thompson, 1979). The highest sea level in Queensland is 3m a.s.l, recorded by a preserved beach ridge at Rainbow Beach (Ward, Little and Thompson, 1979). Potential acid sulfate soils are commonly activated where groundwater tables have been drained for urban and agricultural development, becoming activated when the soil mineral pyrite is consequently oxidized. After rainfall, recharged groundwater tables seep into rivers and estuaries, transporting associated acid and heavy metals into these receiving waters.

In the Mary Estuary, acid sulfate risks occur mainly in association with cane horticulture or urbanization near Maryborough, although the current growth of 0.4% in Maryborough is modest relative to the 5% growth rate in Hervey Bay (Queensland Government, 2007).

FIGURE 2.9: Acid Sulfate Risk in the in the Estuary Section (B) of the Mary River Catchment (A).

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CHAPTER 3

WATER QUALITY IN THE MARY RIVER AND PROJECTIONS TO 2020

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3.1 THE CURRENT CONDITION OF WATER QUALITY IN RELATION TO MANAGEMENT ACTION TARGETS

3.1.1 Estuary and Freshwater concentration values.

The current condition of water quality was assessed using the Guidelines Tool (Marsh et al., 2006), against water quality values developed for the Environmental Values and Water Quality Objectives for the Mary Catchment (chapter 4 of this report; Queensland Environmental Protection Agency, 2006). We sourced data from the Queensland Environmental Protection Agency. Fourteen years of data were used to ensure that the normal range of longer-term cycles, such as El-Nino and monsoon periods, was effectively covered by the current condition assessment.

Results showed that concentrations’ of both filterable reactive phosphorus and total phosphorus in the estuary bordered or exceeded guideline limits in the Mary Estuary Management Unit, and in the Lower Mary Management Unit downstream of Gympie (Table 3.1). Nitrogen species bordered or exceeded guideline limits in the estuary, and at Fisherman’s Pocket in the Lower Mary (close to the Gympie STP). Chlorophyll-a was mostly within guideline limits in the estuary, and borderline in the upper estuary and lower Mary.

Filterable Oxides of Organic Sampling Location Ammonium Total N Reactive Total P Chlorophyll_a Nitrogen Nitrogen Phosphorus

Mary River 6.0km from mouth opposite Horseshoe Brook 1.6 Mary River 12.2km from mouth opposite Crab Island 2.2

Mary River 17.7km from mouth west of Brothers Island Mary River 22.5km from mouth 0.01 0.33 0.338 0.72 0.03 0.07 2.3 Mary River 27.5km from mouth 100m u/s of Saltwater Creek Mary River 32.8km from mouth opposite Aubinville STP discharge Mary River 36.1km from mouth near end of Napier St Maryborough 2.9

Mary River 39.1km from mouth near Little Tinana Creek Mary River 42.2km from mouth 100m u/s of meat works discharge 2.7 Mary River 45.4km from mouth near Brisk Street Mary River 50.2km from mouth 3.95 Mary River 56.7km from mouth - North Bank 0.02 0.08 0.38 0.51 0.02 0.05 4.9

Mary River 91.0km from mouth - West Netherby 0.008 0.01 0.335 0.42 0.02 0.05 4.3 Mary River 170.4km from mouth - Fisherman's Pocket 0.027 0.27 0.37 0.68 0.091 0.12 2.8 Mary River 244.1km from mouth 0.01 0.01 0.218 0.28 0.019 0.03

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Table 3.1: Median nutrient concentrations in the Mary River Catchment. Values for chlorophyll-a are µg/L, and all other nutrients are mg/L. Green symbolizes values within guidelines, orange symbolizes borderline values, and red symbolizes poor values.

Results for physical and chemical parameters (dissolved oxygen, turbidity, and secchi depth readings) were consistently borderline to poor throughout the Estuary Management Zone, although dissolved oxygen readings were within guideline values in the most seaward part of the estuary (Table 3.2). Freshwater sections of the Mary River were within guideline values for dissolved oxygen and turbidity, while pH in the lower Mary was borderline. Note that freshwater measurements stopped 6 years ago in 2002, which predates the extensive accumulation of water hyacinth in the Lower Mary between 2006 and 2007 that substantially lowered dissolved oxygen concentrations in the water column.

Dissolved Turbidity Sampling Location Oxygen (% pH Secchi (m) (NTU) saturation)

Mary River 6.0km from mouth opposite Horseshoe Brook 93 8 1.4 5 Mary River 12.2km from mouth opposite Crab Island 89 7.9 0.6 16

Mary River 17.7km from mouth west of Brothers Island 88 7.9 0.4 29 Mary River 22.5km from mouth 85 7.8 0.3 44 Mary River 27.5km from mouth 100m u/s of Saltwater Creek 79 7.7 0.2 62 Mary River 32.8km from mouth opposite Aubinville STP discharge 76 7.6 0.2 59 Mary River 36.1km from mouth near end of Napier St Maryborough 76 7.6 0.2 68.5

Mary River 39.1km from mouth near Little Tinana Creek 77 7.6 0.2 75 Mary River 42.2km from mouth 100m u/s of meat works discharge 80.5 7.7 0.2 56 Mary River 45.4km from mouth near Brisk Street 83 7.8 0.3 40 Mary River 50.2km from mouth 84 7.8 0.4 29 Mary River 56.7km from mouth - North Bank 87 7.8 0.5 19

Mary River 91.0km from mouth - West Netherby 95 8 11 Mary River 170.4km from mouth - Fisherman's Pocket 103 8 8 Mary River 244.1km from mouth 7.6 3 Table 3.2: Median physical-chemical parameters in the Mary River Catchment. Green symbolizes values within guidelines, orange symbolizes borderline values, and red symbolizes poor values.

3.1.2 Development of local guideline concentration values as targets for on- ground delivery of River-care and Land-care management actions.

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The ANZECC Guidelines recommend tailoring guidelines for local or site specific conditions, which represent modified ecosystems with varying levels of ecosystem disturbance. It is important that the target ecosystem condition represents a level of protection consistent with the water quality objectives for the local resource (chapter 4), and an outcome that is achievable and has stakeholder support.

To effectively evaluate improvements to water quality within the Burnett Mary Region that might result from voluntary Landcare and Rivercare projects, the Burnett Mary Regional Group and the Mary River Catchment Coordinating Committee have monitored local reference sites and test sites. Local reference sites were nominated as “target reaches” that management actions aspire to achieve, while test sites were nominated as reaches that require better management to reach the target condition. These sites were chosen by catchment representatives involved with Rivercare and Landcare activities, to represent river sections where there is local interest to achieve voluntary initiatives. Of relevance, the nominated local reference sites during the 2007-08 period were similar to or below the Queensland Guidelines, except for oxides of nitrogen and total suspended solids in the lowland section. Data from June 2007 – June 2008 are shown in Table 3.3.

Nutrient (mg/L) Lowland Qld Lowland Local Headwater Qld Headwater Local Guidelines (mg/L) Reference Sites Guidelines (mg/L) Reference Sites (mg/L) (mg/L) Ammonia 0.02 0.024 0.01 0.006

Oxides of Nitrogen 0.06 0.136 0.04 0.082

Filterable Reactive 0.02 0.007 0.015 0.006 Phosphorus Total Phosphorus 0.05 0.046 0.03 0.017 (persulfate) Total Nitrogen 0.5 0.473 0.25 0.17 (persulfate) Total Suspended 6 8.56 6 1.18 Solids Table 3.3: Water Quality in target reaches compared with Queensland Guideline values.

The outcome of this water quality investigation in the headwater rivers, was that Imbil and Pickering Bridge in the Upper Mary require better management of total nitrogen, nitrite and ammonia contributions from upstream sources (i.e. managing total nitrogen loads entering the stream), and the rivers capacity to process these nutrients (i.e. supporting ecological processes in the streams that assimilate or remove nitrogen). Camboon Bridge and Pickering Bridge require better upstream management of phosphorus and total suspended solids to achieve water quality consistent with the Little Yabba Creek reference sub-catchment (Figure 3.1).

In the lowland river sections, Widgee Crossing and Pioneers Rest had high total nitrogen concentrations, compared with the Cooran reference reach in Six Mile Creek. At Widgee Crossing, soluble nitrogen and total phosphorus were also above the nominated reference concentrations. At Traveston Crossing and Home Park, soluble phosphorus was above reference concentrations. Consequently management actions are required upstream of Widgee Crossing, Traveston Crossing, Pioneers Rest, and Home Park with respect to better nutrient management (Figure 3.2).

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Figure 3.1: Mary River Headwater Streams: 2007- 08 condition with respect to intended River-care and Land-care activities. The line represents the nominated reference condition (80th percentile of Little Yabba Creek data), and yellow box-plots represent sites above this reference condition.

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Figure 3.2: Mary River Lowland section: 2007- 08 condition with respect to intended River-care and Land-care activities. The line represents the nominated reference condition (80th percentile of the Cooran site data), and yellow box-plots represent sites above this reference condition.

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3.1.3 Herbicide and Pesticide Risks in Fresh Waters

Herbicide concentrations in river water measured by McMahon et al., (2005), the Burnett Mary Regional Group, and the Mary River Catchment Coordinating Committee (Table 3.4, Figure 3.3) were predominantly well below current freshwater trigger values (Queensland Environmental Protection Agency, 2006: http://www.epa.qld.gov.au/publications?id=1414)

Desethyl Desisopropyl Management Unit River Atrazine Diuron Hexazinone atrazine atrazine Lower Mary Myrtle Creek * * * * * Tinana Tinana * * Munna Creek * * Western Mary Wide Bay Creek Upper Mary Mary River

Management Unit River Bromacil Simazine Imidacloprid Metalochlor Lower Mary Myrtle Creek * Tinana Tinana * * * * Munna Creek Western Mary Wide Bay Creek * Upper Mary Mary River * Table 3.4: Herbicides and pesticides found in rivers of the Mary Catchment in 2007-08.

There is no evidence of a problem, but it needs to be noted that guidelines are based around the “safe” concentrations for individual pesticides and herbicides, with no guidelines regarding cocktails of different chemicals. Little is known about the effect of herbicide cocktails below the recommended “safe” concentration, or as an indirect ecosystem pressure on food resources such as green algae. The combined effect could be of ecological significance. Because this needs investigation and advice from experts in this field, there is still a significant lack of knowledge regarding herbicides and pesticides in our streams (Colin Limpus, pers. comm.).

Atrazine warrants mention because Hayes et al., (2002) found that low environmental concentrations of atrazine (0.01 µg/L) can influence the sex ratios of frogs during early larval development, which has prompted some countries to consider restricting its use. The Australian Pesticides and Veterinary Medicines Authority (2004) noted inconsistencies between several studies at replicating low dose effects on amphibians, the influence of other stressors, and the occurrence of healthy amphibian populations at sites where atrazine occurs. On this basis the APVMA is not convinced that atrazine is impacting adversely on populations of Australian amphibians at current exposure rates such as the concentrations found in the Mary River.

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Figure 3.3: Maximum concentrations of some herbicides measured in streams of the Burnett Mary Region (McMahon et al., 2005; Burnett Mary Regional Group, unpublished baseline data). Sampling was done between 2002-04 (McMahon et al., 2005), and 2007-08 (BMRG & MRCCC).

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3.1.4 Herbicide and Pesticide Risks in Marine Waters

There is a paucity of information regarding herbicide and pesticide concentrations in the marine receiving waters of Hervey Bay. Herbicide concentrations at the river mouth or in river water measured by McMahon et al., (2005) and the Burnett Mary Regional Group were predominantly well below current trigger values (Great Barrier Reef Marine Park Authority, 2008), but border on sub-lethal concentrations that might occasionally suppress photosynthesis in some marine species (Table 3.5).

Concentration (µg/L) for a specified level of Maximum concentration (µg/L) Maximum concentration (µg/L) Herbicide or protection (%) from sub-lethal suppression of measured at the Mary River's measured in rivers of the Mary pesticide photosynthesis in marine species mouth Catchment 99% 95% 90% Diuron 0.01 0.06 0.1 0.105 0.07 Atrazine 0.4 0.8 1.3 0.01 0.68 Ametryn 0.2 0.4 0.7 <0.005 0.01 Default GBRMPA guidelines Simazine 0.2 3.2 4.15 0.09 Table 3.5: Threshold concentrations for protecting marine ecosystems from the sub-lethal effects of herbicides. Measured environmental concentrations are listed in the right columns.

McMahon et al., (2005) showed that diuron was the main herbicide detected in sea-grass habitats (up to 0.05µg.l-1), with simazine and atrazine being detected during moderate flow events (Table 3.5). This study identified low background concentrations of these compounds during periods of low river flow, which caused no detectable photosynthetic stress in seagrass. However during moderate flows following rainfall, herbicide concentrations in seagrass habitats increased to values known to affect seagrass photosynthesis. Based on measured concentrations McMahon et al., (2005) believed that there was an associated risk to seagrass. In a companion study, Bengtson Nash et al., (2005) tested seagrass photosynthesis at concentrations encountered in Hervey Bay, and measured a 3% suppression of photosynthetic activity at the environmental concentrations found during moderate flows. The findings of Bengtson Nash et al., (2005) support suggestions that seagrass habitats in Hervey Bay are at risk of periodic exposure to sublethal concentrations of herbicides.

Fringing coral reefs occur on Woody Island at the mouth of the Mary River. The symbiotic algae in corals are sensitive to herbicides at low concentrations (Jones, 2005). For example a ten minute exposure to diuron concentrations of 0.25µg.l-1 has been shown to reduce the photosynthetic efficiency of algal symbionts in coral (Jones and Kerswell, 2003). Although recovery in tank tests was rapid, photo-inhibition seems to act as a cue for corals to expel their algal symbionts and it may take months for the symbiosis to re-establish (Jones, 2005). As with seagrass habitats, coral reefs may be a risk of periodic exposure during wet season freshes.

It needs to be noted that herbicide concentrations measured in the Mary River to date (McMahon et al., 2005; BMRG and MRCCC, unpublished data) are below values known to significantly influence coral viability (cited by Jones, 2005). Furthermore concentrations measured in rivers will be subject to further dilution by mixing with stormwater, and seawater in Hervey Bay. The possible effect of temporary low-level photosynthetic inhibition on coral viability caused by herbicides is a valid concern, which needs to be considered in the context of other stressors that could contribute greater ecological disturbance, such as smothering by sediment, hyper-salinity, exposure to freshwater, and cold periods.

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3.1.5 Groundwater Dependent Surface Water Systems in the Upper Mary Headwaters.

Groundwater-stream connections were monitored in Obi Obi Creek, to better understand the role of groundwater in nutrient enrichment that has caused algal blooms in this creek (Todd, 2008a). The investigation area is a raised plateau formed on Tertiary Basalt, with groundwater measurements (recharge from Standing Water Level and daily rainfall, nutrients, cations and anions, and e-coli faecal indicator bacteria) done in parallel with stream measurements.

This study confirmed that groundwater is drawn from two overlying aquifers, with some mixing of groundwater between aquifers. There is a strong connectivity between the aquifer and Obi Obi Creek. A 3D Visualisation model of the area has been developed in conjunction with Queensland University of Technology.

Nitrate concentrations were elevated above natural background (0.05 mg/L NO3_N) at most bores in the upper aquifer, and at all stream sites, regardless of antecedent rainfall conditions. After rainfall, nitrate enrichment can occur in some bores but not others, without obvious pattern. Nitrate is initially enriched in streams and then diluted by additional rainfall. Most bores in non-sewered rural residential areas show nitrate enrichment in the upper aquifer, while the lower aquifer has naturally low nitrate levels.

Background phosphorus concentrations were high, reflecting probably a basalt influence. Only two bores had PO4_P concentrations above background (0.1 mg/L), and these bores were located in non-sewered rural residential areas. Stream orthophosphate concentrations were only periodically above ANZECC guidelines for upland streams.

There was intermittent e-coli contamination at a few bore sites, which may have been related to contamination within the bore. There was however consistent e-coli contamination at all stream sites.

3.1.6 Groundwater Dependent Surface Water Systems associated with coastal zone development.

The Woodgate community investigated groundwater condition under the Woodgate township (Todd, 2008b), in response to a perceived risk of sea-water intrusion in the area, and a change to a centralised STP from previously non-sewered urban subdivisions. Management improvements are hoped to result from these actions.

Todd (2008b) observed that groundwater is hosted by two distinct geological units, Quaternary Coastal Sands and the Tertiary Elliott Formation (sands and gravel). Quaternary Coastal Sands occur along the coastal margin, so observations made here can be related to similar township development along the coast (e.g. Tin Can Bay).

Groundwater recharge from local rainfall is hosted by a single aquifer combining the geological units, and typically occurs when a rainfall event exceeds a threshold value of 35-40mm as a rule of thumb. On the basis of Standing Water Level (SWL) response to event rainfall, it is estimated that 47% of annual rainfall is lost due to evapotranspiration; 39% recharges directly to groundwater, while a surface runoff component amounting to 19% of annual rainfall occurred during a few very intense rainfall events. A significant proportion of this runoff probably later recharged to groundwater due to local drainage system configuration and the sandy nature of local soils. The conversion from septic tanks to the centralised STP is of minor consequence to groundwater

Mary Catchment Water Quality Improvement Plan - 49 -

recharge because typical wastewater discharge from the town comprises only 6% of direct groundwater recharge.

There was no major evidence of seawater incursion caused by current rates of groundwater extraction at Woodgate. However, a long standing high salinity area exhibiting a seawater influence, and periodic high electrical conductivity near the base of some bores nearest the beach are evidence of the vulnerability of this town to localised seawater incursion.

The change to a centralised STP has resulted in a discernable improvement in dissolved nitrogen and phosphorus in groundwater at Woodgate. However, dissolved Nitrogen levels remain well above ANZECC guidelines locally, due possibly to overuse of garden fertilisers on sandy soils. Locally high concentrations of dissolved nutrients in groundwater may be a potential issue for aquatic ecosystems that receive Woodgate groundwater discharge, which include seagrass beds directly offshore and the adjacent Burrum National Park wetland. A community based seagrass monitoring program based in this region has recorded periodic recurrences of epiphytic algae overgrowing seagrass leaves in the intertidal zone (Gordon Cottle, pers. comm.), but a link between these overgrowths and nutrients or other factors has not been investigated.

3.2 WATER QUALITY TRENDS IN RELATION TO RESOURCE CONDITION TARGETS

Time series data of the QEPA ambient monitoring program were analysed to represent nutrient variations over time, and identify long term trends and seasonal variations within the datasets. The purpose of doing this is to:

1) Project trends with respect to time frames for short term management actions and long term resource condition targets. 2) Allow trends of water quality improvements to be distinguished from existing seasonal and temporal trends.

There is a portion of existing variation in water quality that stakeholders in the Mary Catchment can manage (e.g. land management practices that contribute loads to receiving waters), and another portion that stakeholders cannot control (e.g. time, discharge, temperature, tides, seasons). This chapter identifies the dependency of water quality condition indicators on a seasonal driver (time), landscape drivers (temperature, discharge), and pressures (excess nutrients). Appendix 1 identifies the portion of water quality that can be realistically managed by stakeholders, and partitioned for the purpose of target setting. For example 33% of variation of total nitrogen in the Mary estuary depends on discharge (Figure 2 in Appendix 1), so the remaining 67% is at least partly influenced by upstream management actions. This interpretation process makes it possible to monitor and evaluate the partitioned 67% of TN in the Mary estuary for reporting purposes.

3.2.1 Nutrient trends in the Mary Catchment

Time series analyses of nitrogen concentrations in the Mary estuary showed declining trends in the lower estuary at the 22.5km site for total nitrogen (0.20mg/L per decade) and oxides of nitrogen (0.13mg/L per decade), and no long term change in the central estuary at the 56.7km site. The former site is the interface between the marine and channel geomorphic zones in the Mary Estuary, and the latter site is in the channel geomorphic zone just downstream of the tidal barrage. Seasonal cycles for total nitrogen were observed annually, with high nitrogen concentrations occurring slightly more frequently during the wet season. The 56.7km site also had a 4.4 year

Mary Catchment Water Quality Improvement Plan - 50 -

cycle. Unlike total nitrogen, cycles of ammonia and total oxides of nitrogen can peak throughout the year. Cycles of varying frequencies ranged between 6 months and 6½ years for ammonia, total oxides of nitrogen, and organic nitrogen (Figure 3.4).

1.6 1.6 Total Nitrogen at 22.5km R2 = 0.28 Total Nitrogen at 56.7km R2 = 0.16 1.4 1.4 Actual Actual 1.2 Predicted 1.2 Predicted 1 1

0.8 0.8 TN TN

0.6 0.6

0.4 0.4

0.2 0.2

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

0.8 0.8 Oxides of Nitrogen at 22.5km R2 = 0.25 Oxides of Nitrogen at 56.7km R2 = 0.14

Actual Actual 0.6 Predicted 0.6 Predicted x x 0.4 0.4 NO NO

0.2 0.2

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

1.2 1.2 Organic Nitrogen at 22.5km R2 = 0.12 Organic Nitrogen at 56.7km R2 = 0.18

1 Actual 1 Actual Predicted Predicted 0.8 0.8

0.6 0.6 Organic Organic N Organic N 0.4 0.4

0.2 0.2

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

0.1 0.1 Ammonia at 22.5km R2 = 0.23 Ammonia at 56.7km R2 = 0.15

0.08 Actual 0.08 Actual Predicted Predicted

0.06 0.06

0.04 0.04 Ammonia Ammonia

0.02 0.02

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

Figure 3.4: Nitrogen trends in the Mary Estuary Management Zone.

Total phosphorus concentrations in the estuary are gradually declining at the 22.5km site (0.04mg/L per decade), with 1 and 6½ year cycles (Figure 3.5). Phosphorus concentrations during the wet season tended to be higher. At the 56.7km site, seasonal cycles had periods of 5 to 7 months, 1 year, 2 years, and 6½ years. Filterable reactive phosphorus is also declining at the 22.5km site (0.012mg/L per decade), and has seasonal cycles (1, 1.3, 2.6, and 4.4 years). At the 56.7km site, seasonal filterable reactive phosphorus occurs as 1, 2, and 4.4 year cycles. Like total phosphorus, the highest concentrations of filterable reactive phosphorus occur during the wet season.

Mary Catchment Water Quality Improvement Plan - 51 -

0.30 0.30 Total Phosphorus at 22.5km R2 = 0.34 Total Phosphorus at 56.7km R2 = 0.29

0.25 Actual 0.25 Actual Predicted Predicted 0.20 0.20

0.15 0.15 TP TP

0.10 0.10

0.05 0.05

0.00 0.00 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

0.08 Filterable Reactive Phosphorus at 22.5km 2 0.08 Filterable Reactive Phosphorus at 56.7km 2 R = 0.26 R = 0.19 Actual Actual 0.06 Predicted 0.06 Predicted

0.04 0.04 FRP FRP

0.02 0.02

0.00 0.00 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

Figure 3.5: Phosphorus trends in the Mary Estuary Management Zone.

Chlorophyll a varied seasonally in various parts of the estuary, with periods between 2 months and possibly 13 years (Figure 3.6). Annual cycles were observed at all sample locations, with amplitudes increasing with distance from the river’s mouth. At the 6.0km sample site (in the lower estuary, and the marine geomorphic zone) there is a declining trend (1.24 µg/L per decade) of chlorophyll a concentration, but this decline does not occur elsewhere in the estuary.

30 Chlorophyll a at 22.5km 2 30 Chlorophyll a at 56.7km 2 R = 0.09 R = 0.09

24 Actual 24 Actual Predicted Predicted

18 18 Chl a 12 Chl a 12

6 6

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

Figure 3.6: Chlorophyll a trends in the Mary Estuary Management Zone.

Nutrient trends in freshwater

Time series models were developed to understand temporal variations in total nitrogen concentrations along the main-stem Mary River (Figure 3.7), at sampling points 91.0km (the NRW Gauge 138014A at Home Park), 170.4km (the NRW Gauge 138007A at Fishermans Pocket, slightly downstream of the Gympie STP outflow), and 244.1km (25.9km downstream from the NRW Gauge 138110A at Bellbird). The former two sites are in the Lower Mary Management Zone, and the latter site is in the Upper Mary Management Zone. No long term changes were observed, but seasonal cycles in the lower Mary occurred annually and at 4¼ years. Amplitudes of seasonal trends were more pronounced at the 91.0km site than at the 170.4km and 244.1km sites.

Mary Catchment Water Quality Improvement Plan - 52 -

1.6 1.6 Total Nitrogen at 91.0km R2 = 0.18 Total Nitrogen at 244.1km R2 = 0.17 1.4 1.4 Actual Actual 1.2 Predicted 1.2 Predicted 1 1

0.8

TN 0.8 TN

0.6 0.6

0.4 0.4

0.2 0.2

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

0.8 2 0.8 Oxides of Nitrogen at 91.0km R = 0.23 Oxides of Nitrogen at 244.1km R2 = 0.18 Actual Actual 0.6 Predicted 0.6 Predicted x x 0.4 0.4 NO NO

0.2 0.2

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

1.2 1.2 Organic Nitrogen at 91.0km R2 = 0.18 Organic Nitrogen at 244.1km R2 = 0.12

1 Actual 1 Actual Predicted Predicted 0.8 0.8

0.6 0.6 Organic N 0.4 Organic N 0.4

0.2 0.2

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

0.1 Ammonia at 91.0km 2 0.1 Ammonia at 170.4km 2 R = 0.08 R = 0.04 Actual 0.08 0.08 Actual Predicted Predicted

0.06 0.06

0.04

Ammonia Ammonia 0.04

0.02 0.02

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

Figure 3.7: Nitrogen trends in the Lower Mary Management Zone (91km; 171km sample points), and the upper Mary Management Zone (244.1km sample point).

Total phosphorus has annual and 4¼ year cycles at all freshwater sites (Figure 3.8). Seasonal cycles in the Lower Mary Management Zone were of greater amplitude than in the Upper Mary site. Filterable reactive phosphorus also has annual cycles at all freshwater sites (amplitudes of 0.006 and 0.005 mg/L at the 91.0 and 244.1km sites respectively), and 8½ year cycles at the lower Mary sites (amplitude of 0.008 at the 91.0km site). Filterable reactive phosphorus shows large seasonal fluctuations at the 170.4km site, where sewage treatment plant outflows have influence.

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0.15 0.15 Total Phosphorus at 91.0km R2 = 0.21 Total Phosphorus at 244.1km R2 = 0.20

Actual Actual Predicted Predicted 0.10 0.10 TP TP

0.05 0.05

0.00 0.00 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

0.08 0.08 Filterable Reactive Phosphorus at 91.0km R2 = 0.37 Filterable Reactive Phosphorus at 244.1km R2 = 0.13

Actual Actual 0.06 Predicted 0.06 Predicted

0.04 0.04 FRP FRP

0.02 0.02

0.00 0.00 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

Figure 3.8: Phosphorus trends in the Lower Mary Management Zone (91km sample point), and the upper Mary Management Zone (244.1km sample point).

At all freshwater sites, chlorophyll a concentrations follow seasonal cycles with an amplitude of 2 µg/L (Figure 3.9). At the 244.1km site, there were significant cycles of 8.5-10 months (1 µg/L amplitude) and 2 - 4¼ years (1 µg/L amplitude).

30 Chlorophyll a at 91.0km 30 Chlorophyll a at 244.1km R2 = 0.18 R2 = 0.18

24 Actual 24 Actual Predicted Predicted

18 18 Chl a 12 Chl a 12

6 6

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

Figure 3.9: Chlorophyll a trends in the Lower Mary Management Zone (91km sample point), and the upper Mary Management Zone (244.1km sample point).

Stepwise multiple linear regression models were also developed (Appendix 1), to indicate the dependency of nutrient concentrations (TN_N and TP_N as mg/L) on landscape drivers. The same analytical approach was used to indicate the dependency of primary production (chlorophyll a -1 concentrations) on bio-available nutrients (NOx_N, NH3_N, Org_N, FRP_P as mg.L ), water column turbidity (Nephelometric Turbidity Units as NTU), and water temperature (T as oC). These models explained the dependency of 20-40% of variation with respect to chlorophyll a concentrations (Appendix 1). Collectively these analyses represent links between landscape pressures, water quality vectors, and the ecological condition of primary production, in various management units of the Mary Catchment.

For example, in the Lower Mary Management Unit there were observable differences between the 91.0km (Fishermans Pocket) and the 170.4km (Home Park) sites with respect to the relative effects of discharge, which had opposite influences at the two sites. This likely relates to the

Mary Catchment Water Quality Improvement Plan - 54 -

proximity of the 170.4 km to the Gympie STP outlet, where discharge at Fisherman’s Pocket would dilute concentrations that are proximal to the point source, whereas at the 170.4 km site discharge would attenuate nutrients from the STP and other downstream sources.

3.2.2 Physical-chemical trends in the Mary Catchment

Conductivity in the estuary

Time series analyses of conductivity in the Mary estuary were done at 12 sampling points. Salinity has increased over time in lower estuary, in the marine geomorphic zone and the seaward part of the channel zone (Figure 3.10). Furthermore seasonal cycles have varied in amplitude across the estuary. Seasonal variations were most pronounced in the mid estuary waters, of the channel geomorphic zone, between 15 and 30km from the mouth. Here 1 and 4.4 year cycles have the greatest fluctuation (Figure 3.11). Nearer the barrage, cycles of 2 and 6.6 years were also measured. These cycles decreased in amplitude with distance from the estuary mouth.

70 Conductivity at 6km 70 Conductivity at 22.5km C) C)

o 60 o 60

50 50

40 40

30 30 2 R = 0.20 2 20 20 R = 0.20 Actual 10 10 Actual Conductivity (mS/cmConductivity 25 at Conductivity (mS/cmConductivity 25 at Predicted Predicted 0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

70 Conductivity at 36.1km 70 Conductivity at 56.7km R2 = 0.16 R2 = 0.13 C) C) 60 60 o o Actual Actual 50 Predicted 50 Predicted 40 40

30 30

20 20

10

10 (mS/cmConductivity 25 at Conductivity (mS/cmConductivity 25 at

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

Figure 3.10: Conductivity trends in the Mary Estuary Zone.

9 Decadal change in 8 1 year electrical conductivity C) o 8 2 year C) C) o 7 4.4 year 7 6.6 year 6 6 5 5 4 4 3 3 2 2

1 1 Electrical conductivity (mS/cm at 25 at (mS/cm conductivity Electrical 0 25 at (mS/cm cycle seasonal of Amplitude 0 0 10 20 30 40 50 60 0 10 20 30 40 50 60 distance from rivermouth distance from rivermouth

Figure 3.11. Left graph: The change in electrical conductivity (mS/cm at 25oC) per decade in the Mary River estuary, with respect to position from the river mouth. Right graph: Amplitudes of 1, 2,

Mary Catchment Water Quality Improvement Plan - 55 -

4.4 and 6.6 year seasonal cycles, of electrical conductivity in the Mary River estuary, with respect to position from the river mouth.

The greatest variations in estuarine conductivity occur between 15 and 30km from the estuary mouth with respect to continuous long term change as well as seasonal fluctuations.

Conductivity in freshwater

Time series analyses of conductivity in the Lower Mary Management zone were done at 91.0km (Home Park) and 170.4km (Fishermans Pocket), and in the Upper Mary Management Zone at the 244.1km sample point (downstream of Bellbird). An annual cycle with an amplitude 60-90 µS/cm at 25oC was measured at all locations (Figure 3.12). There was a statistically insignificant suggestion of an 8½ year cycle, which needs to be confirmed by ongoing monitoring. There was a decline in conductivity at the 170.4km site (120 µS/cm at 25oC per decade), which has declined from high conductivities measured in 1994 and 1995. This decline may continue, or may stabilize at conductivities measured between 1999 and 2001. Again, this needs to be confirmed by ongoing monitoring.

0.8 Conductivity at 91.0km 0.8 Conductivity at 244.1km R2 = 0.23 C) C) o o Actual 0.6 0.6 Predicted

0.4 0.4

R2 = 0.30 0.2 0.2 Actual 25 at (mS/cm Conductivity 25 at (mS/cm Conductivity Predicted 0.0 0.0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

Figure 3.12: Conductivity trends in the in the Lower Mary Management Zone (91km sample point), and the upper Mary Management Zone (244.1km sample point).

Dissolved Oxygen in the estuary

Dissolved oxygen concentrations (% saturation) were measured at 12 points in the Mary Estuary Management Zone. Long term improvements were observed in the lower estuary in the marine geomorphic zone (Figure 3.13), downstream of the 22.5km sampling point, with dissolved oxygen increasing by between 5% and 7% per decade. Annual cycles were observed, with amplitudes of 3-6% saturation. Between the 45.4km and 50.2km sampling points, seasonal amplitudes were much less pronounced. There were instances in the channel geomorphic zone where dissolved oxygen dropped to below 60% saturation, in sub-monthly time frames, which is biologically significant because low dissolved oxygen is a known ecological pressure associated with fish kills.

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120 Dissolved Oxygen at 6.0km 120 Dissolved Oxygen at 22.5km 110 110

100 100

90 90

80 80

2 2 DO (% DO saturation) 70 R = 0.20 DO (% saturation) 70 R = 0.19

60 Actual 60 Actual Predicted Predicted 50 50 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

120 Dissolved Oxygen at 36.1km 120 Dissolved Oxygen at 56.7km R2 = 0.11 R2 = 0.19 110 110 Actual Actual 100 Predicted 100 Predicted

90 90

80 80

DO (% DO saturation) 70 DO (% (% DO saturation) 70

60 60

50 50 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time Figure 3.13: Dissolved oxygen trends in the Mary Estuary Zone.

Dissolved Oxygen in freshwater

Dissolved oxygen concentrations in the Lower Mary River had annual cycles. At Home Park (NRW gauge 138014) there was a slight decrease over the long term (6.5% per decade) in dissolved oxygen concentrations. High frequency 3.8 month cycles with amplitudes of 6% saturation were observed in the upper Mary (Figure 3.14). Monitoring of dissolved oxygen in freshwater sections ceased in 2002, so periods when hyacinth mats extensively covered 18.2 km of the lower Mary have not been represented by this record. Recent observations directly underneath hyacinth mats have measured dissolved oxygen being consistently low, with associated with fish kills (Steve Burgess, pers. comm.).

120 Dissolved Oxygen at 91.0km 120 Dissolved Oxygen at 244.1km 110 110

100 100

90 90

80 80

2 2 R = 0.15 70 R = 0.09 DO DO (% saturation)

DO (% DO saturation) 70

60 Actual 60 Actual Predicted Predicted 50 50 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time Figure 3.14: Dissolved oxygen trends in the Lower Mary Management Zone (91km sample point), and the upper Mary Management Zone (244.1km sample point). pH in the estuary

Estuarine pH varied annually by amplitudes of between 0.06 and 0.17 pH units, depending on position from the river mouth (Figures 3.15 and 3.16). Statistically significant cycles occurred at 6.6 year, 3.3 year, 2.6 year, and 3-5 month periods, at various sampling points in the estuary. While being statistically significant, cycles of monthly variation are not large enough to be biologically

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significant. Variations that occur in shorter time frames are much larger, and possibly biologically significant.

There were no long term trends in the estuary, except for a decrease in pH by 0.12 pH units per decade in the marine zone at the 6km sample point.

9.4 pH at 6km 2 9.4 pH at 22.5km 2 R = 0.07 R = 0.09 9.0 9.0 Actual Actual 8.6 Predicted 8.6 Predicted 8.2 8.2

pH 7.8 7.8 pH

7.4 7.4 7.0 7.0

6.6 6.6

6.2 6.2 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

9.4 pH at 36.1km 2 9.4 pH at 56.7km 2 R = 0.06 R = 0.17 9.0 9.0 Actual Actual 8.6 Predicted 8.6 Predicted 8.2 8.2

7.8 7.8 pH pH

7.4 7.4

7.0 7.0 6.6 6.6

6.2 6.2 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

Figure 3.15: pH trends in the Mary Estuary Zone.

0.18 y = 0.067Ln(x) - 0.115 0.16 R2 = 0.925

0.14

0.12

0.1

0.08

0.06 amplitude of pH cycle 0.04

0.02

0 0 10 20 30 40 50 60 distance from rivermouth

Figure 3.16: The amplitude of annual cycles of pH in the Mary Estuary Zone, with respect to position from the river mouth.

Mary Catchment Water Quality Improvement Plan - 58 -

pH in freshwaters

In the Lower Mary, pH varied annually with amplitudes of 0.2 pH units and every 4-5 months (amplitudes between 0.08 to 0.16 pH units), and at the 91.0km site (Home Park) every 2 months (amplitudes of 0.08pH units). At the 170.4km site (Fishermans Pocket) and the 244.1km site (25.9km downstream of Bellbird) there was a 4 year cycle with an amplitude of 0.11 – 0.19 pH units. While pH variations over monthly cycles may be biologically unimportant, variations in the sub-monthly time frame may be biologically significant (Figure 3.17).

9.4 9.4 pH at 91.0km 2 pH at 244.1km 2 R = 0.15 R = 0.20 9.0 9.0 Actual Actual 8.6 Predicted 8.6 Predicted 8.2 8.2 7.8 7.8 pH pH

7.4 7.4

7.0 7.0

6.6 6.6

6.2 6.2 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

Figure 3.17: pH trends in the Lower Mary Management Zone (91km sample point), and the upper Mary Management Zone (244.1km sample point).

Light penetration in the estuary

Light penetration has increased in the lower estuary in the marine geomorphic zone (1.1m per decade at the 6km sample point, 55cm per decade at 12.2km), and in parts of the mid estuary at the extreme perimeters of the channel zone (8cm per decade at 22.5km, and 13cm per decade at the 56.7km site). There has been no long term change at the mid estuary sites between 22.5 and 56.7km, except for the 32.8km site where light penetration has decreased by 10cm per decade (Figure 3.18).

Light penetration has annual cycles with amplitudes of 4-6 cm, with larger amplitude annual cycles (13cm) at the 6km and 56.7km sites. This may be biologically significant to benthic primary production on shallowly sloping sand bars and mangrove flats.

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5.0 5.0 Light penetration at 6.0km Light penetration at 22.5km 2 R = 0.15

4.0 4.0 Actual Predicted

3.0 3.0

2.0 2.0 R2 = 0.38 Light penetration(m) Lightpenetration (m) 1.0 1.0 Actual Predicted 0.0 0.0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

5.0 5.0 Light penetration at 36.1km 2 Light penetration at 56.7km 2 R = 0.10 R = 0.17

4.0 Actual 4.0 Actual Predicted Predicted

3.0 3.0

2.0 2.0 Light penetration (m) Lightpenetration (m) 1.0 1.0

0.0 0.0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time Figure 3.18: Light penetration in the Mary Estuary Zone.

Water temperature in the estuary and freshwater

Water temperature throughout the Mary River and its estuary varies annually, with an amplitude of 4oC that ranges between 20 and 28oC (Figure 3.19).

Mary Catchment Water Quality Improvement Plan - 60 -

35 35 Temperature at 6.0km 2 Temperature at 22.5km 2 R = 0.40 R = 0.57

30 30 C) C) o o

25 25 Temperature( 20 Temperature ( 20 Actual Actual Predicted Predicted 15 15 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

35 35 Temperature at 36.1km 2 Temperature at 56.7km 2 R = 0.58 R = 0.59

30 30 C) C) o o

25 25 Temperature ( 20 Temperature ( 20 Actual Actual Predicted Predicted 15 15 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

35 35 Temperature at 91.0km 2 Temperature at 244.1km 2 R = 0.39 R = 0.36

30 30 C) C) o o

25 25 Temperature( Temperature ( 20 20 Actual Actual Predicted Predicted 15 15 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time Figure 3.19: Temperature variations in the Mary Estuary Management Zone (6km, 22.5km, 36.1km, 56.7km), Lower Mary Management Zone (91km), Upper Mary Management Zone (244.1km).

Turbidity in the estuary

The marine zone has an annual turbidity cycle (Figure 3.20). There is statistically insignificant suggestion of longer cycles (3, 7 and 13 year trends) in various parts of the estuary, which need to be confirmed by continued monitoring. Furthermore, turbidity has decreased in the marine zone (4.3NTU and 8.2NTU per decade at 6.0 and 12.2km), but increased in the central zone between the 27.5 and 50.2km sample sites (Figure 3.21).

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200 200 Turbidity at 6.0km 2 Turbidity at 22.5km 2 R = 0.13 R = 0.17 Actual Actual 150 Predicted 150 Predicted

100 100 Turbidity (NTU) Turbidity (NTU) 50 50

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time

200 200 Turbidity at 36.1km 2 Turbidity at 56.6km 2 R = 0.08 R = 0.06 Actual Actual 150 Predicted 150 Predicted

100 100 Turbidity (NTU) Turbidity(NTU) 50 50

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time Figure 3.20: Turbidity variations in the Mary Estuary Management Zone. 90

80

70

60

50

40

30

20 Changein turbidity(NTU) decade per 10

0 0 10 20 30 40 50 60 distance from rivermouth

Figure 3.21: The rate of increase in turbidity in the mid estuary section of the Mary River.

Turbidity in freshwaters

The Lower Mary Management Zone has an annual turbidity cycle (amplitude of 5 - 17 NTU). At the 170.4km site (Fishermans Pocket) there is also a shorter 2 month turbidity cycle (amplitude of 5 NTU) (Figure 3.22).

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200 200 Turbidity at 91.0km 2 Turbidity at 170.4km 2 R = 0.12 R = 0.23 Actual Actual 150 Predicted 150 Predicted

100 100 Turbidity (NTU) Turbidity (NTU) 50 50

0 0 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 1/31/1993 7/24/1998 1/14/2004 7/6/2009 12/27/2014 6/18/2020 Time Time Figure 3.22: Turbidity variations in the Lower Mary Management Zone (91km) and Upper Mary Management Zone (244.1km).

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3.3 SEDIMENT AND NUTRIENT LOADS IN THE MARY CATCHMENT, AND PROJECTION OF LOADS WITH RESPECT TO MANAGEMENT OPTIONS.

Managing the condition of receiving waters depends on managing the delivery of sediment, nutrient, and herbicide loads entering receiving waters from upstream sources, so that the water quality objectives required of the Mary Catchment are achieved while maintaining appropriate environmental values. Projections of sediment and nutrient generation in the Mary Catchment, and exported to freshwater and marine receiving waters, have been developed by various approaches:

1) Landscape modelling of end of catchment loads, with proposed management actions such as Rivercare and Landcare modelled as scenarios (DeRose et al., 2002; Fentie et al., 2006; Esslemont et al., 2006b). 2) Sub-catchment and plot-scale measurements of sediment, nutrient, and herbicide runoff (Hunter & Armour, 2001; Costantini et al., 1999; Loch, 2000; Costantini & Loch, 2002; Stork, Bennett & Bell, 2007). 3) Sediment analyses for phosphorus concentrations in excess of background, which can be related to anthropogenic or natural enrichment in landscape patches (Burnett Mary Regional Group unpublished data).

To indicate the influences of various parts of the Mary River upon sediment and nutrient loads, and the outcomes of management actions upon catchment water quality, the outputs of these studies are summarised.

3.3.1 Improvements to catchment load delivery projected by landscape modelling. The SedNet model represents relative sediment generation, transport, and end of catchment delivery so that dominant processes are understood, and geographical areas that contribute the majority of the load can be identified. The outcomes of the model are (a) projections of sediment loads based on best available information, (b) identification of gaps in information that limit the accuracy of these projections, and (c) “best guess” interpretations that can be drawn from the model. Projections of sediment (Figure 2.7), total nitrogen and total phosphorus exports (DeRose et al., 2002) from the Mary Catchment are given in section 2.3 of this report.

A high proportion of sediment exported to the coast comes from areas adjacent to the main river channel (DeRose et al., 2002), particularly from the Lower Mary Management Unit downstream of Gympie (suspended sediment loads exported to the coast from eroding banks typically are over 2 t/ha/year). The Mary River Catchment Coordinating Committee have developed a Mary River and Tributaries Rehabilitation Plan (http://mrccc.org.au/publications.html), which includes revegetation of degraded sections of river to improve riverine habitat and manage bank erosion. The options of (a) revegetating the priority reaches identified by this plan, and (b) revegetating reaches purely to manage erosion control, were modelled in terms of reducing sediment export into Hervey Bay (Esslemont et. al., 2006c):

(a) MRCCC River Rehabilitation Plan scenario y = -0.0058x2 + 0.6532x - 0.3025 (R2 = 0.9955) y = Percentage reduction in suspended sediment exported to Hervey Bay. x = Percent of degraded bank revegetated (%).

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However if initial revegetation efforts focus on firstly stabilizing the banks most vulnerable to erosion (i.e. ignoring other ecological outcomes), then limiting sediment export to Hervey Bay will be achieved more quickly through option b. Option b would achieve a theoretical 24% reduction in sediment export if 60% of eroding banks are stabilised:

(b) Prioritization of the most vulnerable reaches y = -0.0086x2 + 0.9229x + 0.4857 (R2 = 0.9939).

The other major source of sediment export to the coast comes from diffuse sources across the landscape, associated with the management of pasture cover on grazing land (because grazing is the dominant land-use in the Mary Catchment). The Queensland Department of Primary Industry together with the Mary River Catchment Coordinating Committee have established a grazing land management program (http://mrccc.org.au/projects.html), designed to manage diffuse erosion particularly from hill-slopes. The outcome of this program in terms of reducing sediment export into Hervey Bay has also been modelled (Esslemont et. al., 2006d), starting from an assumed 50% pasture cover (level C category of cover). Achieving an 80% pasture cover (level A category of cover) from this baseline would give theoretical reduction in sediment export into Hervey Bay of 31%: y = 1.06x – 53.4 (R2 = 0.9943).

When considering targets based on proportional improvements, it needs to be noted that the starting point of 50% pasture cover may be an unrealistically low generalization because level B pasture cover appears to be the predominant category in the Mary (Shields, 2005). Regardless of the baseline starting point, the Sednet model projected improvements to sediment export close to a 1:1 ratio with percent of grazing land improvement. Therefore simply reporting on area of pasture improvement is a meaningful metric with respect to projected end of catchment loads.

Other modelling approaches have been used to project improvements to sediment and nutrient loads from various business proposals. The Lake Baroon Catchment Care Group have developed a catchment plan to address sheet erosion and stormwater derived loads entering Obi Obi Creek in the Upper Mary Management Unit. They anticipate the following improvements: TSS reductions by 29-43%, TN reductions by 20-31%, and TP reductions by 19-33% (Lake Baroon Catchment Care Group, 2007). The Queensland Dairy Organisation developed a competitive tender approach to improve riparian buffer strips, and lessen nutrient discharge into receiving waters by better wastewater management. They projected a 0.1115% reduction in total nitrogen and a 0.099% reduction in total phosphorus contributed to Hervey Bay from tenders developed by 14 dairy farms (Queensland Dairyfarmers Organisation, 2008).

3.3.2 Measured off site movement of sediment, nutrients, and herbicides from cane, forestry, mining, and main roads.

There have been several plot to farm scale investigations into sediment and nutrient exports from various landuses: sugarcane, tree crops, forestry, mine-sites, and main roads. Sediment generation rates vary with multiple interacting factors: rainfall intensity, rainfall period, slope, slope length, soil type, level of soil disturbance associated with land-use, vegetative cover. Sediment generation rates were: 30 – 0.01 T/ha for suspended sediments, 4 – 0.23 kg/ha for nitrogen, 0.5 – 0.015 kg/ha for phosphorus. Results from these experiments are listed in table 3.6.

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Table 3.6: Sediment and nutrient loads generated at the plot scale. Nitrogen Rainfall Sediment Load Phosphorus Landuse Slope (%) Soil Rainfall (mm) period Scale (ha) Fertilizer added load (T/ha) (kg/ha) load (kg/ha) Study

54% sugarcane; Hydrosol>> 17% roads & Dermosol> Average wet Hunter & drains - Sodosol season 2 years Catchment (790) Yes 1.3 0.2 Armour, 2001

85% sugarcane; 15% roads & Average wet Hunter & drains - Hydrosol season 2 years Farm (45) Yes 3.4 0.4 Armour, 2001

86% sugarcane; 14% roads & Average wet Hunter & Sugar drains 0.5 Hydrosol season 2 years Block (4) Yes 2.8 0.5 Armour, 2001

Average wet Hunter & Sugarcane 0.5 Hydrosol season 2 years Plot (0.14) Yes 1.6 0.4 Armour, 2001 Below average Podosol or wet season Stork, Bennett Sugarcane 1 dermosol (180) 1 year Plot (0.22) Yes 0.093 0.6 0.2 & Bell, 2007

Below average Tree horticulture wet season Stork, Bennett (macadamias) 3 Kandosol (300) 1 year Plot (0.48) Yes 0.01 0.3 0.3 & Bell, 2007 Tree horticulture 2/3 of plots (pine): freshly Simulated 1 in fertilised. Residual Tree crops Tree mounded 10 year event 30 fertiliser in soil from Costantini & upslope 2 Kandosol (48) minutes Plot historic use. 0.8±0.3* 4±1 0.5±0.1 Loch, 2002 * represents the fine scale sediment fraction mobilised off-site (coarser sediments were mobilised, but most remained on-site).

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Nitrogen Rainfall Sediment Load Phosphorus Landuse Slope (%) Soil Rainfall (mm) period Scale (ha) Fertilizer added load (T/ha) (kg/ha) load (kg/ha) Study

Pine 2/3 of plots forestry:freshly Simulated 1 in fertilised. Residual mounded 10 year event 30 fertiliser in soil from Costantini & upslope 1 Kandosol (48) minutes Plot historic use. 0.24±0.02* 1.5±0.2 0.3±0.1 Loch, 2002

Pine forestry: 2/3 of plots freshly Simulated 1 in fertilised. Residual mounded 10 year event 30 fertiliser in soil from Costantini & downslope 1 Kandosol (48) minutes Plot historic use. 0.22±0.05* 0.9±0.3 0.1±0.04 Loch, 2002

Pine forestry: Aged (8 2/3 of plots months) Simulated 1 in fertilised. Residual Pine forestry forestry Pine mounded 10 year event 30 fertiliser in soil from Costantini & upslope 1 Kandosol (48) minutes Plot historic use. 0.8±0.3* 2±1 0.4±0.1 Loch, 2002

Pine forestry: Traditional landuse, Simulated 1 in clearfell logged 10 year event 30 Costantini & & stick raked 5 Kandosol (48) minutes Plot Not fertilised 0.3±0.1* 0.23±0.07 0.015±0.005 Loch, 2002

* represents the fine scale sediment fraction mobilised off-site (coarser sediments were mobilised but usually remained on-site).

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Nitrogen Rainfall Sediment Load Phosphorus Landuse Slope (%) Soil Rainfall (mm) period Scale (ha) Fertilizer added load (T/ha) (kg/ha) load (kg/ha) Study

Costantini, Sandy material 20 Loch, Connolly, Pine forestry 5.8 on road base 33 minutes Plot (0.0006) Not fertilised 0.77 Garthe, 1999. Sandy surface over hard road base (50% Costantini, cover by litter 20 Loch, Connolly, Pine forestry 5.1 or grass) 33 minutes Plot (0.0006) Not fertilised 0.49 Garthe, 1999.

Gravel road - Costantini, some fine, 20 Loch, Connolly, Pine forestry 4.8 loose gravel 33 minutes Plot (0.0006) Not fertilised 2.14 Garthe, 1999. Gravel road - some hard surface, some Costantini, coarse loose 20 Loch, Connolly, Pine forestry 9.8 gravel 33 minutes Plot (0.0006) Not fertilised 2.19 Garthe, 1999. Ungravelled, grass free

Forestry Roads Forestry road, fine textured Costantini, surface 20 Loch, Connolly, Norfolk pine 5.7 material 33 minutes Plot (0.0006) Not fertilised 3.17 Garthe, 1999.

Costantini, As above - 10 Loch, Connolly, Norfolk pine 5.7 wheeltracked 15 minutes Plot (0.0006) Not fertilised 2.65 Garthe, 1999.

Costantini, Fine textured 20 Loch, Connolly, Norfolk pine 12.5 gravel road 33 minutes Plot (0.0006) Not fertilised 1.64 Garthe, 1999.

Costantini, Fine textured 20 Loch, Connolly, Norfolk pine 7.9 gravel road 33 minutes Plot (0.0006) Not fertilised 1.91 Garthe, 1999.

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Nitrogen Rainfall Sediment Load Phosphorus Landuse Slope (%) Soil Rainfall (mm) period Scale (ha) Fertilizer added load (T/ha) (kg/ha) load (kg/ha) Study

Sandy loam Simulated 1 in topsoil over a Rehabilitated 15 100 year event sandstone mined land. 0% (65) 30 mullock dump. grass cover minutes Plot (0.0018) Not fertilised 30 Loch, 2000. Sandy loam Simulated 1 in topsoil over a Rehabilitated 15 100 year event sandstone mined land. (65) 30 mullock dump. 23% grass cover minutes Plot (0.0018) Not fertilised 15 Loch, 2000. Sandy loam Simulated 1 in topsoil over a Rehabilitated 15 100 year event sandstone Mining mined land. (65) 30 mullock dump. 37% grass cover minutes Plot (0.0018) Not fertilised 3 Loch, 2000. Sandy loam Simulated 1 in topsoil over a Rehabilitated 15 100 year event sandstone mined land. (65) 30 mullock dump. 47% grass cover minutes Plot (0.0018) Not fertilised 1.3 Loch, 2000. Sandy loam Rehabilitated Simulated 1 in topsoil over a mined land. 15 100 year event sandstone 100% grass (65) 30 cover mullock dump. minutes Plot (0.0018) Not fertilised 0.6 Loch, 2000.

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Suspended sediment, total nitrogen and total phosphorus event-based loads have been measured by QNRW (http://www.wqonline.info/products/infoanddata.html) from various streams in the Mary Catchment. Furthermore long term records (1982-2002) of total suspended sediments and discharge were used to estimate long term sediment loads (t/ha/year) transported from all upstream sources. It is important to note that this procedure will estimate sediment loads, but significant gaps in information limits the accuracy of this estimation, because several major events were not captured.

Between June 2007 and December 2008, baseline community event sampling done by the MRCCC for the WQIP successfully sampled most events that occurred that year from the Upper Mary Management Unit (sampled at Gympie and/or Traveston Crossing) and the Lower Mary Management Unit (sampled near Home Park and/or from Maryborough).

Table 3.7 illustrates how load intensities vary as a function of time and area, which means that loads measured at different spatial scales (Table 3.7, Figure 2.7) and temporal scales (Figure 2.6) are not commensurate. This is important when considering the various loads estimates presented in this report; high loads from some landscape patches predicted by Sednet (Figure 2.7) come from a relatively small unit area, when compared with apparently lower loads measured at gauging stations from much larger contributing areas (Table 3.7).

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Table 3.7.

Long term projection Landscape of sediment Management Unit & Maximum load Nitrogen gauging station Catchment Discharge Rainfall Sediment (T/ha/year Load Phosphorus Landuse (km2) Total Flow (ML) (m3/s) Rainfall (mm) period load (T/ha) 1982-2002) (kg/ha) load (kg/ha) Reference

60% dairy, 10% 100% of upstream Catchment Not Not grazing, 10% 7,210 103 catchment received 3 days 3.615 0.962 NRW (26) measured measured rural residential, 250 - 450mm 5% vegetable GS138120A) (NRW Gauge

Gardiners Falls Gardiners and fruit crops.

50% of upstream 37,658 494 NRW 47% nature catchment received conservation; 150 - 450mm 4 days 0.005 0.350 0.062 27% grazing Catchment 50% of upstream and dairy, 10% 35,534 588 0.125 NRW (486) catchment received rural residential,

138110A) 100 - 350mm 1 day 0.16 1.008 0.267 manufacturing 100% of upstream and services Not Not

Bellbird (NRW Gauge 250,767 2,814 catchment received 4 days 2.7 NRW measured measured 400 - 700mm

31% grazing, 50% of upstream 26% nature 93,937 635 catchment received 3 days 0.003 0.315 0.091 NRW conservation, 150 - 450mm Catchment 18% forestry, 0.151 Upper Mary Upper (2097) 13% rural 100% of upstream Not Not 771,002 5,803 4 days 0.90 NRW Dagun (NRW Dagun (NRW residential & catchment received measured measured Gauge 138109A) services. 400 - 700mm

100% of upstream Not 556 3 catchment received 8 days 0.038 0.003 NRW measured 25 - 75mm 35% dairy; 35% nature 100% of upstream conservation; Catchment 1,549 12 catchment received 3 days 0.011 0.150 0.015 NRW 0.232 20% grazing; (80) 125 - 175mm 10% rural residential. 100% of upstream Not 1,008 6 catchment received 4 days 0.065 0.004 NRW measured

Cooran (NRW CooranGauge (NRW 138107B) 25 - 50mm

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Long term projection Landscape of sediment Management Unit & Maximum load Nitrogen gauging station Catchment Discharge Rainfall Sediment (T/ha/year Load Phosphorus Landuse (km2) Total Flow (ML) (m3/s) Rainfall (mm) period load (T/ha) 1982-2002) (kg/ha) load (kg/ha) Reference

34% grazing; 80% of upstream 25% nature Not 6,482 90 catchment received 2 days 0.041 0.006 NRW conservation; measured 50 - 125mm 17% forestry; Catchment Not 8% rural (2663) measured

138020A) residential; 6% Upper Mary Upper dairy; 4% pine 50% of upstream forest. 15,942 328 catchment received 8 days 0.012 0.090 0.013 NRW Gympie (NRW Gauge Gympie (NRW 75 - 200mm

20% of upstream Not Not 901,391 2,812 catchment received 3 days 0.104 NRW measured measured 47% grazing; 50 - 175mm 18% nature Catchment conservation; 20% of upstream 0.235* (6845) Not Not 13% plantation 1,481,374 4,976 catchment received 1 day 0.584 NRW 138014A) measured measured Lower Mary Lower Mary forestry 50 - 125mm Not 400,220 1,184 Not obtained 0.104 0.679 0.079 BMRG Home Park (NRW Gauge (NRW Park Home obtained 25% grazing; 100% of upstream 25% nature Not Not 5,933 100 catchment received 2 days 0.100 NRW conservation; measured measured Catchment 75 - 175mm 25% plantation 0.065 (100) forestry; 10% 100% of upstream Not rural residential; 899 10 catchment received 6 days 0.090 0.010 NRW Tagigun (NRW measured Gauge 138009A) 10% vegetable 50-75mm 37% pine forest,

Tagigun 100% of upstream 21% nature Not Not 55,677 181 catchment received 16 days 0.033 NRW conservation, measured measured Catchment 100 - 350mm 16% grazing, 0.028 (783) 9% forestry, & 50% of upstream catchment received

Bauple (NRW (NRW Bauple 5% rural 8,221 23 10 days 0.003 0.128 0.009 NRW Gauge 138903A) residency. 25-50mm

*Because of better capture of events data at the Miva gauge, the long term sediment load projection (T/ha/yr) was developed from the Miva gauge instead of the Home Park gauge.

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3.3.3. Phosphorus measured in river sediment

A BMRG investigation identified where phosphorus exceeded background ratios normally associated with iron oxides in river sediment. Excess phosphorus can result from natural provenance (e.g. geology) or human factors (e.g. sewage outfall, fertiliser additions). Recently deposited mud drapes left by the most recent event (24th August – 11th September 2008, which exported 54 tons of total phosphorus into Hervey Bay) were sampled from rivers or riverbanks in the Mary Catchment.

Excess phosphorus scavenged by iron oxides were highest in river sediment deposited as a concentration gradient downstream from the Maleny Basalts (20-8x background). The Maleny Basalt has 0.27 – 0.66 P2O5 (%wt) (Todd, 2008a), compared to 0.16 %wt in the average continental crust (Taylor and McLennan, 1985). In the Mary Catchment samples were not collected close to sewage treatment plants outlets, but in the Burnett excess phosphorus commonly occurs within 1 km of STP outlets (11-7x background). The Dickabram Bridge site in the Lower Mary had excess phosphorus, possibly associated with a localised concentration of cattle faeces that had settled with fine sediment at the waters edge where the sample was collected. These results indicate that better management of soil erosion from basaltic headwaters, STP effluent (e.g. land- based disposal), and possibly protecting riparian zones from cattle access, would give returns for target investments aimed towards managing phosphorus in the Mary River.

River sediment sampled from the lower section of Tinana Creek, in the Lower Mary Irrigation Area, did not have excess phosphorus in the fine sediment (Figure 3.23), though it was evident that sediment had recently been washed into receiving streams from surrounding tilled horticultural lands (Figure 3.24). Because the measurable threshold of the analytical procedure used to target iron bound phosphorus was ±5x background, this sediment study may not have been able to resolve possible phosphorus signals from horticultural practices in the LMIA.

Figure 5.24. Sampling location in a creek immediately downstream from tilled land. Evidence of sediment mobilisation include sand-bars. A bob-cat had been used to dig sediment out of this creek.

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Figure 3.23: Sediment-bound phosphorus concentrations (µM.g-1) in stream sediments of the Burnett Mary Region (Burnett Mary Regional Group, unpublished baseline data). Sampling was done in 2007-08. Concentrations are the measured enrichment of phosphorus above natural concentrations expected in iron oxide and carbon minerals.

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3.3.4 Best available projections of sediment and nutrient additions to receiving waters.

Collectively information about the supply of sediments and nutrients into the Mary River indicate:

1) Relatively high sediment loads are generated by hillslope erosion and riverbank erosion in the Upper Mary and Western Mary Management Zones, and riverbank erosion in the Lower Mary Management Zone. Sediment entry into the river carries diffuse contributions of nitrogen and phosphorus.

2) Relatively high sediment loads are generated by mine sites and forestry roads, from a combination of soil disturbance, slope and rainfall. However the small area occupied by these land- uses limit their relative contribution at the catchment scale. Significant sediment and nutrient loads can also be generated from forestry and horticulture (cane, tree crops, forestry) when intense rainfall hits disturbed soil. Management actions that retain cover (e.g. trash blanketing with cane horticulture, retaining residue biomass on hillslopes with pine forestry) and minimise soil disturbance are possible management actions that can lessen off-site movement of sediment.

3) Above average phosphorus additions to river sediment are associated with erosion of soils developed over basalt from the Upper Mary Management Zone, and potentially with STP outfalls in the Estuary Management Zone (Maryborough STP) and Lower Mary Management Zone (Gympie STP).

3.4 WATER QUALITY WITH RESPECT TO RESOURCE CONDITION TARGETS

A resource condition target (RCT) is a long term target representing outcomes over large spatial and temporal scales (e.g. catchment scale changes over 50 years), achieved by the sum of management actions implemented over 10 to 20 year time frames in targeted parts of the catchment. Setting these targets requires projection of how the catchment is trending with respect to water quality vectors, and some understanding of processes that may limit or enhance the desired RCT. Trends and processes are summarized below.

3.4.1 Hervey Bay and Great Sandy Straits

Sediment, total nitrogen and total phosphorus exports from the Mary catchment into the Hervey Bay and Great Sandy Straits receiving waters are modelled to be respectively (Kilotonne per year): 455, 1.541, 0.344. Since European settlement, relative erosion rates delivered from some sections of the Western Mary have increased 2 to 7 fold, and 4 to more than 14 fold in the Upper Mary. Sediment and nutrient delivery is essential for the seagrass ecosystem of Hervey Bay, but large events are occasionally known to extensively smother seagrass with resultant ecosystem collapse.

The prevailing vector of long-shore transport of sediment northward along the continental shelf has been removed in Hervey Bay by the shielding effect of Fraser Island (http://www.fido.org.au/Boyd.pdf), but long-shore transport recommences north of Hervey Bay. Wave based re-suspension of sediment during cyclones, which is normally associated with long- shore mobilisation of sediment (Larcombe and Carter, 2004; Figure 3.24), is limited by low wave heights. Wave-heights of 6.4 - 8.6 meters in the outer bay and 3.3 – 3.5 meters in Great Sandy

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Straits are the maximum expected during cyclone events (Hardy et al., 2004). Hence sediment would accumulate in the basin below the wave base (Boyd et al., 2004), as sediment banks stabilized by sea-grass.

Figure 3.24. Sediment plumes associated with a regional scale wet-season event (February 21st – 22nd, 2008), showing northward movement of suspended sediment along the coast. The satellite image was sourced from the Environmental Remote Sensing Group at CSIRO Land & Water. The white bar at the bottom right hand side of the image is 89km.

Discharge is important for balancing salinity in Hervey Bay, to counteract hyper-saline conditions that develop during dry periods. High density, saline water sinks down-slope and exits the bay along low-lying seabed contours (and ultimately off the edge of the continental shelf). The density current is an important vector for water movement out of the bay during ambient conditions.

3.4.2 The Mary Estuary Management Unit There were high concentrations of all nutrients in the Mary River estuary relative to the Queensland Water Quality guidelines, and these concentrations vary seasonally, which indicates a strong nutrient base for primary production. The time series analyses showed that the marine geomorphic zone (the lower estuary seaward of the 22.5km sample point) could be distinguished from the central zone (the mid estuary landward of the 22.5km sample point) with respect to water quality.

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The marine zone is currently in poor condition relative to Queensland guideline values (Queensland Environmental Protection Agency, 2006), but improvements are occurring with respect to total nitrogen, total phosphorus, oxides of nitrogen, and filterable reactive phosphorus. The landscape driver that underpins this trend appears to be a marine transgression that has occurred over the last decade as a result of low discharge from the Mary River. If this trend continues, a resource condition target for these nutrients closer to the Queensland Guidelines should be achievable in the Marine Zone.

Conductivity is increasing in the marine zone, which has received diminished freshwater inputs since the 1990’s. Seasonal variations are most pronounced at the 22.5km site, which is the junction between the central zone and marine zone. Landward of the 22.5km site the estuary is less saline.

In the central zone all nutrient species have remained stable over the last decade, in poor condition relative to the Queensland Water Quality Guidelines. Nutrient concentrations and availabilities vary seasonally, and appear to be influenced significantly by natural drivers (Appendix 1). A resource condition target close to the Queensland Guidelines may be harder to achieve landward of the 22.5km sample point because the estuary is still developing (Saintilan, 1996), and because the Mary Barrage acts as a barrier to medium and low flows through the estuary. The central estuary zone with the barrage lacks a base flow to transport nutrients seaward. Long term residents have commented on rapid sediment deposition in the channel zone over the last 40 years (Tiaro Landcare, pers. comm.), by contrast with the historical condition of an un-dredged channel that allowed seagoing ships to berth at Maryborough.

Primary production in the water column is limited by light penetration, turbidity, temperature, and nutrient availability (Appendix 1). In the marine zone light penetration has increased while turbidity has decreased. Declining nutrient concentrations have corresponded with declining primary production, despite improving light penetration. Hence an improved resource condition target with respect to nutrients in the Marine Zone should be readily achievable because chlorophyll a concentrations are improving.

In the channel zone turbidity has increased while light penetration has remained low or decreased. This low light condition limits primary production and associated eutrophication risks (despite high nutrient concentrations), which leads to lower dissolved oxygen concentrations as a consequence of limited primary production (Appendix 1). Dissolved oxygen concentrations in this section of the estuary are poor relative to the Queensland Water Quality Guidelines. Because the central zone of the Mary River is becoming more turbid, the capacity of the system to improve dissolved oxygen levels as a function of primary production will become even more limited. It is important to note that the Mary Estuary is tide dominated and at an immature stage of development (Saintilan, 1996), therefore turbid conditions and increasing turbidity are expected as a natural process. Decreasing stream flow caused by a dry decade and the installation of the barrage, has possibly accelerated sediment deposition rates in the channel zone.

In the channel zone immediately downstream from the barrage, at the 56.7km site, light penetration has increased while turbidity has remained constant. Primary production measured by chlorophyll a concentrations at the 56.7km site is stable, and occasionally above the guideline value, indicating a seasonal risk of eutrophication with ecologically significant fluctuations in dissolved oxygen concentrations. pH in the estuary is buffered by carbonate in seawater. There is potential for acid sulfate discharges to influence pH in the estuary (Figure 2.9) if they are not adequately managed. Wiithout

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significant tidal mixing to replenish bicarbonate this influence may develop as a significant pressure.

3.4.3 The Lower Mary Management Unit Home Park has borderline water quality with respect to oxides of nitrogen, phosphorus and chlorophyll a when referenced against the Queensland Guidelines. Upstream at Fisherman’s Pocket results for all phosphorus and nitrogen species, except for organic nitrogen, were also borderline or poor although chlorophyll a concentrations were within guideline values. The Fishermans Pocket site had strong annual cycles for ammonium, and borderline concentrations relative to guideline values. This is significant because the high pH (8) of this river section means that ammonia, a toxic gas to aquatic fauna, is stable and may be an ecosystem pressure during summer. Organic N concentrations at this site have declined at a rate of 0.17mg/L per decade since 1994. This is significant because this site is influenced by discharges from the Gympie Sewage Treatment Plant, and this decline might represent improved management.

Despite the improvements to organic nitrogen concentrations at Fisherman’s Pocket, results for most nutrient concentrations have been stable over time. Nutrient release from riverbed sediment could limit the potential of the Fishermans Pocket reach to improve with respect to nutrient management, specifically with respect to oxides of nitrogen and ammonia that are produced by nitrifying bacteria in the sediment. Therefore changes to nutrient and photosynthetic behaviour may be a challenging management action target. However eutrophication can be controlled by limiting light availability using riparian trees, and limiting phosphorus bio-availability in the water column by using Phoslock (www.clw.csiro.au/new/2006/phoslock.html). Land based re-use of effluent from the Gympie Sewage Treatment Plant would be an outcome that contributes to water quality improvements in the Lower Mary River.

In summary primary production seasonally influences the high pH measured at Home Park and Fisherman’s Pocket, which is relevant to ammonia in the water column. Strategies such as maintaining riffles using environmental flows could be a feasible way of managing the consequences of stratification in pools and weirs, and dispersing ammonia built up in stagnant zones. Improved management of nutrients entering the lower Mary River might improve river condition with respect to nutrients. Light limitation through riparian re-vegetation might assist with managing eutrophication in some river sections with favorable aspect, noting that the river section between Gympie and Fishermans Pocket has a moderately intact riparian zone that offers shade (Johnson, 1997), but does not prevent hyacinth infestations.

3.4.4 The Upper Mary Management Unit

In the Upper Mary, all water quality parameters measured at the 244.1km site are currently within the Queensland Water Quality Guidelines, except for filterable reactive phosphorus (FRP) which is stable at borderline concentrations. Discharge is a weak control on filterable reactive phosphorus (11% of the variation on FRP depends on discharge), which influences chlorophyll-a concentrations (together with ammonium concentrations, light, and water temperature). Bunn et al. (1999) identified riparian canopy cover as being the most important control of gross primary production, followed by the proportion of land cleared for pasture. Several NHT2 funded projects inform where and how nutrients enter the Mary River headwaters (discussed in sections 2.3, 3.1.3, and 5.3), and therefore where landscape re-vegetation and improved farming practices might be prioritized to provide shading and absorb nutrients from groundwater seeps and overland flow. These foundation activities should help to guide the delivery of projects in the Mary River headwaters, to address water quality in downstream river sections.

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3.5 WATER QUALITY WITH RESPECT TO ASPIRATIONAL TARGETS

An aspirational target represents a more immediate outcome, over shorter spatial and temporal scales compared with Resource Condition Targets. These are outcomes that will be achieved by management actions implemented during the next NHT round, in prioritised parts of the catchment (e.g. reach or sub-catchment scale improvements over 5 – 10 years). Setting these targets requires the coordinated application of various initiatives and capabilities of the rural community, to halt or reverse undesirable trends with respect to water quality parameters. These can build on several projects that were initiated during the NHT2 round in the Burnett Mary Region, and will be addressed in chapter 5.

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CHAPTER 4

ENVIRONMENTAL VALUES AND WATER QUALITY OBJECTIVES OF THE MARY RIVER AND MARINE RECEIVING WATERS

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4.1 ENVIRONMENTAL VALUES

Environmental Values (EV’s) are defined in ANZECC Guidelines as “the particular values or uses of the environment that are important for a healthy ecosystem or for public benefit, welfare, safety or health and that require protection from the effects of pollution, waste discharges and deposits. Several environmental values may be designated for a specific waterbody”

The process of establishing EV’s and Water Quality Objectives (WQO’s) is a foundational activity for preparing a WQIP, which is done in accordance with Environmental Protection Policies (EPP Water) under the Environmental Protection Act 1994 (section 1.4 of this report) as part of the NWQMS (section 1.2 of this report). The purpose of the EPP (water) is to provide a framework for:

• identifying EV’s for Queensland Waters • deciding and stating water quality guidelines and objectives to enhance or protect EV’s • making consistent and equitable decisions about Queensland waters that promote efficient use of resources and best practice environmental management • involving the community through consultation and education and promoting community responsibility.

Default EV’s are stated in the EPP (Water), which apply if no EV’s are specified for a water body.

Under the NWQMS and the EPP (Water) water quality includes the broader concept of aquatic system health (not just water chemistry) and there are parallels with other planning and legislative frameworks. For example, management goals in the Water Quality Management (WQM) framework are equivalent to ecological outcomes in the WRP framework, and water quality objectives are equivalent to flow objectives. The range of Queensland legislation relevant to WQM include:

• Environmental Protection Act (Qld) 1994 and its associated Environmental Protection Policy (Water) 1997and Amendment 2006 • Water Resources Act (Qld) 1989 (partly repealed, licensing component only now active) • Water Act 2000 replaced the Water Resources Bill 1999 • Integrated Planning Act (Qld) 1997 • Coastal Protection and Management Act (Qld) 1995 • Fisheries Act (Qld) 1994

Environmental Values and WQO’s for the Burrum and Mary catchments were established in 2006, by the Queensland EPA following public consultation and review. The geographical extent of waters addressed by the Mary WQIP is broadly:

• all freshwaters and tributaries of the Mary River;

Mary Catchment Water Quality Improvement Plan - 81 -

• the upper, mid and lower estuary/enclosed coastal waters of the Mary River and Susan River and tidal tributaries including Tinana Creek; • tidal canals, constructed estuaries, marinas and boat harbours and entrance buffers; • wetlands; and • ground waters.

The water quality objectives are intended to achieve outcomes consistent with 3 levels of aquatic ecosystem protection (ANZECC and ARMCANZ, 2000) that were nominated by the consultation process:

• Level 1: High ecological/conservation value ecosystems - effectively unmodified or other highly valued systems • Level 2: Slightly - moderately disturbed ecosystems - ecosystems in which aquatic biological diversity may be adversely affected to a relatively small but measurable degree by human activity • Level 3: Highly disturbed ecosystems - measurably degraded ecosystems of lower ecological value

The Environmental Values for the Mary, Burrum, and adjacent receiving waters are listed in Table 1 of the Mary River Environmental Values and Water Quality Objectives Report. This report is publicly available in electronic format and can be downloaded from the Queensland EPA website: http://www.epa.qld.gov.au/publications/p01841aa.pdf/Mary_River_environmental_values_and_wat er_quality_objectives_Basin_No_138_including_all_tributaries_of_the_Mary_River.pdf.

4.2 WATER QUALITY OBJECTIVES

Table 2 in the Mary River Environmental Values and Water Quality Objectives Report (refer to the above hyperlink) identifies physico-chemical concentrations as Water Quality Objectives needed to support the aquatic ecosystem EV for waters in the Mary Catchment. Some objectives apply to specific areas or water types (such as marinas, lower estuary and Great Sandy Strait) while others apply to more than one water type. Waters of high ecological value are assigned a higher level of protection so more stringent WQO’s apply. Other waters fall into the slightly-moderately disturbed level of protection, for which correspondingly lower WQO’s have been derived.

For example, in the following situation there are several human use EV’s with differing WQO’s for faecal coliform’s (measured as median number of organisms per 100mL):

• stock watering <100 organisms per 100mL • primary recreation (e.g. swimming) <150 organisms per 100mL • secondary recreation (e.g. boating) <1000 organisms per 100mL

The most stringent WQO is that for stock watering (<100 organisms per 100mL) and its adoption would in turn provide faecal coliform WQO’s that protect all the above-identified EV’s.

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Table 3 in the Mary River Environmental Values and Water Quality Objectives Report (refer to the above hyperlink) identifies the general objectives of conceptual models to support riparian needs and consequent benefits to waterway type. This approach considered differing functions of riparian areas rather than the normal approach of nominating a particular width of riparian (e.g. a default value of 25 meters), which is usually difficult to achieve because of current land use. For example to achieve a shading outcome (i.e. to limit light availability to aquatic weeds), a riparian corridor of one row of trees along banks with the correct solar aspect will suffice. To achieve a barrier to intercept nutrients entering streams from groundwater seeps (i.e. to limit nitrogen availability to aquatic weeds) 10 meters is sufficient (Rassam et al., 2008). To achieve a biodiversity corridor (i.e. to maintain ecological structure in a stretch of river) a wider riparian zone is needed.

4.3 ECOLOGICAL CHARACTER DESCRIPTION OF THE GREAT SANDY STRAIT RAMSAR SITE

After completion of the Environmental Values and Water Quality Objectives report, the Queensland EPA subsequently developed an Ecological Character Description of the Great Sandy Strait Ramsar site (Mike Ronan, pers comm. Based on draft Ecological Character Description for Great Sandy Strait Ramsar site).

This report is not yet publicly available, but will be referred because it is highly relevant. Like the EV/WQO’s report, it collated geological and ecological knowledge about the Great Sandy Straits and lists components and processes that support ecosystem services (the five critical components and processes are listed in chapter 2).

Theis site supports a regionally significant area of seagrass beds, mangrove wetlands, intertidal mud and sand banks, coral reefs and sponge gardens, and other estuarine elements that contain species at, or near to, their northern or southern geographical limits. A substantial area of non- forested peat swamp referred to as ‘patterned fens’ occurs within the site. These fens, together with areas of ‘wallum’ heath swamps, support species’ adapted to the prevailing acidic water and substrate.

Fauna of significance are substantial populations of nationally and/or internationally threatened species, a population of at least 20,000 shorebirds comprising at least 20 species; substantial stocks of juvenile and adult fishes, prawns and crabs (many of which are important for commercial and/or recreational harvest), and a relatively large number of species of marine mammals, including several cetaceans.

In terms of human use, Great Sandy Strait includes sites and resources of considerable cultural significance to indigenous Australians and contains natural resources that potentially may be harvested sustainably by indigenous people for traditional purposes. The site’s rich diversity and abundance of natural resources also supports a range of nature-based tourism and recreational activities.

The ECD identified the following ecosystem components and processes as deserving of management attention:

Freshwater Wetlands:

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• Habitat Extent, Condition and Diversity • Hydrology (surface and groundwater inputs) • Physicochemical Components

Estuarine & Marine Wetlands

• Habitat Extent, Condition and Diversity • Hydrology (freshwater flow from catchments; tidal regimes) • Physicochemical Components (water quality)

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CHAPTER 5 COORDINATED MANAGEMENT ACTIONS TO ACHIEVE TARGETS

85 5.1 WATER QUALITY TARGET SETTING

The voluntary adoption of water quality target setting is possible under an adaptive management framework that promotes open and transparent contributions from stakeholders and the wider community. Targets need to be SMART (Specific, Measurable, Achievable, Relevant and Timed), and this can be achieved by several complementary approaches:

1) Modelling. SedNet /ANNEX models have been used to project relative changes that may result from proposed management actions such as improved grazing land management, and stabilising river banks. Time series models have also been used to project water quality changes over management time frames. Outputs of modelling scenarios are discussed in chapters 2 and 3. The limit of the modelling approach is the significant gap in underlying data (e.g. soil mapping, pasture cover, long term seasonal cycles) and ability to predict some processes (e.g. sediment deposition in dams, bank erosion). These gaps cannot be immediately addressed meaning that, while still predicting landscape behaviour to the best of our knowledge, and probably effectively delineating landscape at risk of erosion, models cannot produce an accurate numerical target for end of catchment loads.

2) Remote sensing. Satellite images and aerial photographs are an effective way of getting a historical record of landscape structure, such as the extent of sediment plume movement into marine receiving waters, the extent of benthic habitat cover in marine waters, or the extent of pasture cover on a grazing landscape. The limit of this approach is the lack of process information that underpins dynamic environments (e.g. tidal variation, temperature fluctuation) to allow for the effective management of risks that may lead to undesirable changes in water quality.

3) Monitoring and historical data. Identification of the water quality condition of reference river-sections as a target condition that stakeholders want to achieve by improved management practices. This condition is tested against current water quality, which has been done in the Mary catchment as a before-after-control-impact design (chapters 3 & 4). Landscape processes need to be understood from supporting science or local knowledge for this approach to be effective. The limit of this approach may be lack of ability to predict water quality outcomes in response to management actions.

4) Utilise improved management practice. Address and report on inputs and practices that land managers can readily change, and which correlate with pollution emissions (e.g. increased ground cover and riparian vegetation, modification of fertiliser application). Changes to recognisably better management practices offer measurable targets.

86 Limitations are the same as for 2 and 3, but improved management practices can be modelled and monitored.

Each of these approaches has benefits and limitations with respect to their power to predict and measure water quality improvements, relate to stakeholder capabilities, and therefore get used for setting achievable and voluntary targets. To achieve positive outcomes, targets need to be developed by open and transparent discussion with all stakeholders. Importantly, the strength and weaknesses of the various target setting approaches need to be recognised, addressed by detailed consultations with experts, and discussed among stakeholders. This is because the application of unproven or overly simplistic causal models carries the risk of waste or poor management outcomes.

Topics for discussion comprise the diversity of landuses, soil types, topography, climate, and stakeholder capacity that reflect particular issues within the catchment (chapter 2), management opportunities that can address these issues (this chapter), and the consequences of failure to achieve targets notwithstanding proactive intentions (chapter 6). Specific management options are detailed in appendix 2, as potential actions that are specific and measurable, so can be used to achieve targets.

There are two levels of targets for different time frames; Resource Condition Targets (i.e. a catchment scale problem that needs to be addressed over several decades, such as a reduced sediment and nutrient loads entering marine receiving waters) and Aspirational Targets (i.e. immediate outcomes that can be addressed over short spatial and temporal scales). Aspirational Targets will be reach or sub-catchment scale improvements over 5 – 10 years. An effective way of achieving Aspirational Targets is to use existing capacity and experience developed during NHT2, and work towards long term goals that can be achieved from the combined Aspirational Targets.

Several projects that were initiated during the NHT2 round in the Burnett Mary Region will be listed for discussion in the context of management units. Each management unit is a catchment sub-section with local management issues. This process allows for local ownership and governance of relevant parts of the catchment, while still achieving outcomes for the overall catchment.

87

5.2 MARINE RECEIVING WATERS: HERVEY BAY, GREAT SANDY STRAITS, MARY ESTUARY MANAGEMENT AREA

RESOURCE CONDITION TARGET FOR THE END OF CATCHMENT (WORKING TITLE)

Sediment, nutrient, and herbicides delivered to estuarine and marine receiving waters of the Mary Catchment are stabilised and reduced by 2050.

ASPIRATIONAL TARGETS FOR THE MARINE AND ESTUARY RECEIVING WATERS (WORKING TITLES)

1) Both diffuse and point source loads of sediment, nutrient, and herbicides are consistent with the Environmental Values and Water Quality Objectives of the region. Region-wide standards and best management practices are widely used by 2015.

2) Acid Sulphate Soils – current sites are managed appropriately and related outbreaks are eliminated by 2015.

3) Optimal environmental flows are achieved by WRP/ROPs, developed and implemented throughout the region by 2015.

4) Greater than 75% of water supplied and used is managed by water use efficient practices across irrigation, urban, industrial and other uses by 2015.

5) Groundwater provinces within the coastal sand mass are managed to avoid deterioration in EV/WQO by 2015.

MANAGEMENT ISSUES

1) Improving physical and chemical components of the estuary and marine receiving waters. Nitrogen and phosphorus, dissolved oxygen, and turbidity in the estuary are outside Queensland Guideline values, which may be natural for a tidal estuary and not man made. 2) Managing nutrient loads resulting from sewage effluent, through septic tank leachate and STP discharges. 3) Managing nutrient and herbicide loads from identified stormwater risk zones. 4) Maintaining hydrological regimes in freshwater, estuarine, and marine wetlands. 5) Maintaining the extent, condition, and diversity of habitat associated with in freshwater, estuarine, and marine wetlands. 6) Managing acid sulfate soils, resulting from cleared land and constructed lakes (e.g. Eli Creek in Hervey Bay).

88 7) Managing stormwater delivery onto fringing reefs (e.g. Tuan Tuan Creek in Hervey Bay). This has resulted from clearing of wetlands, installation of drains, and channelisation of stormwater. 8) Managing interception of nutrients entering streams or coastal zones via groundwater seeps. This has resulted from loss of riparian buffer strips, poor septic tank management, and possibly fertiliser overuse in urban settings. 9) Managing environmental hazards resulting from industrial effluent (e.g. Pulgul Creek).

89 EXISTING CAPACITY AND RECENT PROJECTS

Aspir- Manage- BMRG Lead Project ational ment Project Contact Project Title Project Outcomes Organisation Leader Target Issue Number

The project identified areas of poor Maryborough City Urban Stormwater Quality on a sub- Council, PO Box Maryborough City Kylie Matheson catchment basis, and made 1 3 PA0221 110, Marywise Urban Stormwater Council & Amy Gosley recommendations that each Cluster MARYBOROUGH, Council (in the Mary LGAC) can do to QLD 4650 improve Urban Stormwater quality.

Community involvement and PO Box 5499, 29-31 Going with the flow of acid in estuaries: awareness raising with respect to red Wide Bay Water Kelvin Ellengowen Street, effects of acid sulfate soils on 2 6 PA0314 spot. Investigating whether acid sulfate Corporation O'Halloran Urangan, HERVEY recreational fishing in the Burnett Mary outbreaks affect estuarine biota, using BAY, 4655 River monitoring stations.

Stakeholders within the Water Quality Alliance have concerns about suspected acid sulfate runoff into Eli PO Box 5499, 29-31 Creek, have observed fish kills that Wide Bay Water Ellengowen Street, may be related to acid sulfate caused 2 6 PA0084 David Darmody Coastal Water Quality Alliance Officer Corporation Urangan, HERVEY by urban development, and have BAY, 4655 provided the local council with water quality measurements that demonstrate poor water quality in affected sites.

90 The project reviewed efficient Horticulture Communications programme to Bundaberg Fruit & water use options available in the House, 2 Tantitha enhance water efficiency, water 4 Maybe 4 PA0331 Vegetable Matt Dagun horticulture, turf, cut flowers, St, BUNDABERG, security and environmental flow Growers primary industries and urban 4670 outcomes sectors. Community involvement Delivery of incentives to improve PO Box 953, Bundaberg Pilot Water Quality Incentive Project water quality using 6 easy step, 1 3 PA0361 Dale Hollis BUNDABERG, Canegrowers in the Bundaberg Mill area involving a workshop and incentive 4670 payments.

Design of a wetland to passively filter treated sewage to reduce PO Box 114, total suspended solids by 86%, Wetlandcare Artificial wetland project - Camreay 1 3 PA0374 Mark Bayley BALLINA, NSW, biological oxygen demand by 48%, Australia Holdings 2478. total phosphorus by 75%, total nitrogen by 85%, faecal coliforms by 93%.

The main purpose of this activity Horticulture Bundaberg Fruit & was to better understand sediment House, 2 Tantitha Integrated AreaWide Management in 1 3 PA0062 Vegetable Matt Dagun and nutrient contributions to water St, BUNDABERG, diverse farming systems Growers quality from horticultural farm 4670 practices in the region

Private Bag 4, Reference panel addressing the Ashfield Road, Managing offsite exports of management of off site movement 1 3 BSES Limited Barry Callow BUNDABERG, herbicides and pesticides of herbicide and pesticide in sugar 4670 cane

91 One of the purposes of this activity was to better understand Woodgate 63 Mackerel St, Woodgate Groundwater improvements to water quality of 5 8 PA0215 Residents' John Trevor WOODGATE, Investigation Group groundwater resulting from Association 4660 conversion from septics to a sewage treatment plant

92

93

Great Sandy Straits Management Unit

94

95

5.3 LOWER MARY MANAGEMENT AREA

RESOURCE CONDITION TARGET FOR THE LOWER MARY RECEIVING WATERS (WORKING TITLE)

Sediment, nutrient, and herbicides delivered into freshwater receiving waters of the Lower Mary Management Area are stabilised and reduced by 2050.

ASPIRATIONAL TARGETS FOR THE LOWER MARY RECEIVING WATERS (WORKING TITLES)

1) Both diffuse and point source loads of sediment, nutrient, and herbicides are consistent with the Environmental Values and Water Quality Objectives of the region. Region-wide standards and best management practices are widely used by 2015.

2) Concentrations of total nitrogen at Pioneers Rest and Fisherman’s Pocket, and total phosphorus at Fisherman’s Pocket are closer to concentrations at local reference sites by 2015. (mg/L: TN = 0.473; TP = 0.046).

3) Optimal environmental flows are achieved by WRP/ROPs, developed and implemented throughout the region by 2015.

4) Greater than 75% of water supplied and used is managed by water use efficient practices across irrigation, urban, industrial and other uses by 2015.

5) 50% of priority riparian zones (as classified by PAP2.2) are under Rivercare works aimed at Water Quality outcomes by 2015.

6) At least 15% of farmland affected by salt from rising groundwater tables are remediated and managed sustainably by 2015.

MANAGEMENT ISSUES

1) Improving physical and chemical components of the Lower Mary receiving waters. In particular, poor dissolved oxygen concentrations associated with aquatic weed proliferation and low flow. 2) Managing nutrient loads resulting from sewage effluent, through discharges from the Gympie STP and septic tank leachate. 3) Managing sediment, nutrient and herbicide loads from identified stormwater risk zones. 4) Managing the interception of nutrients entering streams via groundwater seeps. This has resulted from loss of riparian buffer strips.

96 5) Managing groundwater tables in salinity hazard zones. 6) Maintaining hydrological regimes in freshwater wetlands. 7) Maintaining the extent, condition, and diversity of habitat associated with freshwater wetlands. 8) Managing poor bank stability, shading, and structural woody habitat cover resulting from loss of riparian vegetation.

97 EXISTING CAPACITY AND RECENT PROJECTS

Aspir- Manage- BMRG Lead Project ational ment Project Contact Project Title Project Outcomes Organisation Leader Target Issue Number

The project identified areas of poor Maryborough City Urban Stormwater Quality on a Kylie Council, PO Box sub-catchment basis, and made Maryborough City 1 3 PA0221 Matheson & 110, Marywise Urban Stormwater recommendations that each Cluster Council Amy Gosley MARYBOROUGH, Council (in the Mary LGAC) can do QLD 4650 to improve Urban Stormwater quality. The project reviewed efficient Horticulture Communications programme to water use options available in Bundaberg Fruit House, 2 5, enhance water efficiency, water the horticulture, turf, cut flowers, 4 PA0331 & Vegetable Matt Dagun Tantitha St, maybe 6 security and environmental flow primary industries and urban Growers BUNDABERG, outcomes sectors. Community 4670 involvement The main purpose of this activity Horticulture was to better understand Bundaberg Fruit House, 2 Integrated AreaWide sediment and nutrient 1 3 PA0062 & Vegetable Matt Dagun Tantitha St, Management in diverse farming contributions to water quality Growers BUNDABERG, systems from horticultural farm practices 4670 in the region Delivery of incentives to PO Box 953, improve water quality using 6 Bundaberg Pilot Water Quality Incentive 1 3 PA0361 Dale Hollis BUNDABERG, easy steps, involving a Canegrowers Project in the Bundaberg Mill area 4670 workshop and incentive payments.

98 Design of a wetland to passively filter treated sewage to reduce PO Box 114, total suspended solids by 86%, Wetlandcare Mark Artificial wetland project - 1 3 PA0374 BALLINA, NSW, biological oxygen demand by Australia Bayley Camreay Holdings 2478. 48%, total phosphorus by 75%, total nitrogen by 85%, faecal coliforms by 93%.

Private Bag 4, Reference panel addressing the Barry Ashfield Road, Managing offsite exports of management of off site 1 3 BSES Limited Callow BUNDABERG, herbicides and pesticides movement of herbicide and 4670 pesticide in sugar cane Outcomes from 40% of bank length stabilised in the Mary Catchment will result is a 15% Mary River reduction in suspended Catchment Brad PO Box 1027, MO5, M07, MO8 Rivercare 1 4, 8 PA0058 sediment emission to Hervey Coordinating Wedlock GYMPIE, 4570. Projects Bay. In the Lower Mary, banks Committee at most risk of erosion are between Gympie and Wide Bay Creek.

99

100

5.4 TINANA CREEK MANAGEMENT AREA

RESOURCE CONDITION TARGET FOR THE TINANA CREEK RECEIVING WATERS (WORKING TITLE)

Sediment, nutrient, and herbicides delivered into freshwater receiving waters of the Tinana Creek Management Area are stabilised and reduced by 2050.

ASPIRATIONAL TARGETS FOR THE TINANA CREEK RECEIVING WATERS (WORKING TITLES)

1) Both diffuse and point source loads of sediment, nutrients and herbicides are consistent with the Environmental Values and Water Quality Objectives of the region. Region-wide standards and best management practices are widely used by 2015.

2) Concentrations of soluble nitrogen (NH3, NOx) and phosphorus concentrations in the farmed upper section of Tinana Creek, and phosphorus and total nitrogen in the forested mid section of Tinana Creek are closer to concentrations at local reference sites by 2015. (mg/L: NH3 = 0.024, NOx = 0.136,TP = 0.046, FRP = 0.007, TN = 0.473).

3) Greater than 75% of water supplied and used is managed by water use efficient practices across irrigation, urban, industrial and other uses by 2015.

4) At least 15% of farmland affected by salt from rising groundwater tables are remediated and managed sustainably by 2015.

5) 50% of priority riparian zones (as classified by PAP2.2) are under Rivercare works aimed at Water Quality outcomes by 2015.

MANAGEMENT ISSUES

1) Maintaining physical and chemical components of the Tinana Creek receiving waters. In particular, managing poor dissolved oxygen concentrations associated with aquatic weed proliferation and low flow. Soluble nitrogen (NH3, NOx) and phosphorus concentrations in the farmed upper section of Tinana Creek were borderline relative to local guideline values, and phosphorus and total nitrogen in the forested mid section of Tinana Creek were also borderline. 2) Managing sediment, nutrient and herbicide loads from identified stormwater risk zones. 3) Managing the interception of nutrients entering streams via groundwater seeps, resulting from loss of riparian buffer strips.

101 4) Managing poor shading and poor structural woody habitat cover resulting from loss of riparian vegetation. 5) Managing groundwater tables in salinity hazard zones. 6) Maintaining hydrological regimes in freshwater wetlands. 7) Maintaining the extent, condition, and diversity of habitat associated with freshwater wetlands.

102 EXISTING CAPACITY AND RECENT PROJECTS

Aspir- Manage- BMRG Lead Project ational ment Project Contact Project Title Project Outcomes Organisation Leader Target Issue Number

The project identified areas of poor Maryborough City Urban Stormwater Quality on a Kylie Council, PO Box sub-catchment basis, and made Maryborough City 1 2 PA0221 Matheson & 110, Marywise Urban Stormwater recommendations that each Cluster Council Amy Gosley MARYBOROUGH, Council (in the Mary LGAC) can do QLD 4650 to improve Urban Stormwater quality. The project reviewed efficient Horticulture Communications programme to water use options available in Bundaberg Fruit House, 2 Maybe 5 enhance water efficiency, water the horticulture, turf, cut flowers, 3 PA0331 & Vegetable Matt Dagun Tantitha St, & 6 security and environmental flow primary industries and urban Growers BUNDABERG, outcomes sectors. Community 4670 involvement. The main purpose of this activity Horticulture was to better understand Bundaberg Fruit House, 2 Integrated AreaWide sediment and nutrient 1 2, 3 PA0062 & Vegetable Matt Dagun Tantitha St, Management in diverse farming contributions to water quality Growers BUNDABERG, systems from horticultural farm practices 4670 in the region. Delivery of incentives to PO Box 953, improve water quality using 6 Bundaberg Pilot Water Quality Incentive 1 2, 3 PA0361 Dale Hollis BUNDABERG, easy steps, involving a Canegrowers Project in the Bundaberg Mill area 4670 workshop and incentive payments.

103 Design of a wetland to passively filter treated sewage to reduce PO Box 114, total suspended solids by 86%, Wetlandcare Mark Artificial wetland project - 1 2 PA0374 BALLINA, NSW, biological oxygen demand by Australia Bayley Camreay Holdings 2478. 48%, total phosphorus by 75%, total nitrogen by 85%, faecal coliforms by 93%.

Private Bag 4, Reference panel addressing the Barry Ashfield Road, Managing offsite exports of management of off site 1 2 BSES Limited Callow BUNDABERG, herbicides and pesticides movement of herbicide and 4670 pesticide in sugar cane Outcomes from 40% of bank length stabilised in the Mary Mary River Catchment will result in a 15% Catchment Brad PO Box 1027, MO5, M07, MO8 Rivercare reduction in suspended 1,5 3,4,7 PA0058 Coordinating Wedlock GYMPIE, 4570. Projects sediment emission to Hervey Committee Bay. Banks that may be at risk of erosion are in the upper section of Tinana Creek.

104

105

5.5 WESTERN MARY MANAGEMENT AREA

RESOURCE CONDITION TARGET FOR THE WESTERN MARY RECEIVING WATERS (WORKING TITLE)

Sediment, nutrient, and herbicides delivered into freshwater receiving waters of the Western Mary Management Area are stabilised and reduced by 2050.

ASPIRATIONAL TARGETS FOR THE WESTERN MARY RECEIVING WATERS (WORKING TITLES)

1) Both diffuse and point source loads of sediment, nutrients and herbicides are consistent with the Environmental Values and Water Quality Objectives of the region. Region-wide standards and best management practices are widely used by 2015.

2) At least 15% of farmland affected by salt from rising groundwater tables are remediated and managed sustainably by 2015.

3) Concentrations of total nitrogen and ammonia (NH3), total phosphorus and filterable reactive phosphorus (FRP) in the Western Catchments are closer to concentrations observed at local reference sites by 2015 (mg/L: lowland sections NH3 = 0.024, TP = 0.046, FRP = 0.007; headwater sections NH3 = 0.006, TP = 0.017, FRP = 0.006).

4) 50% of priority riparian zones (as classified by PAP2.2) are under Rivercare works aimed at Water Quality outcomes by 2015.

MANAGEMENT ISSUES

1) Maintaining physical and chemical components of the Western Mary receiving waters. In particular, managing borderline total nitrogen, total phosphorus, and filterable reactive phosphorus concentrations in Wide Bay and Munna Creeks. 2) Managing sediment, nutrient and herbicide loads from identified stormwater risk zones. In particular managing sediment generated by hill-slope and bank erosion in the Wide Bay and Glastonbury catchments where there is relatively poor vegetation cover and cattle access into creeks. 3) Managing the interception of nutrients entering streams via groundwater seeps, resulting from loss of riparian buffer strips. 4) Managing poor shading and structural woody habitat cover resulting from loss of riparian vegetation. 5) Managing groundwater tables in salinity hazard zones in the Wide Bay Catchment, particularly where there has been clearing of deep- rooted timber for grazing, or areas of improved pasture irrigated by groundwater.

106 6) Maintaining hydrological regimes in freshwater wetlands. 7) Maintaining the extent, condition, and diversity of habitat associated with freshwater wetlands.

107 EXISTING CAPACITY AND RECENT PROJECTS

Aspir- Manage- BMRG Lead Project ational ment Project Contact Project Title Project Outcomes Organisation Leader Target Issue Number

The project identified areas of poor Maryborough City Urban Stormwater Quality on a Kylie Council, PO Box sub-catchment basis, and made Maryborough City 1, 3 1, 2 PA0221 Matheson & 110, Marywise Urban Stormwater recommendations that each Cluster Council Amy Gosley MARYBOROUGH, Council (in the Mary LGAC) can do QLD 4650 to improve Urban Stormwater quality.

Design of a wetland to passively filter treated sewage to reduce PO Box 114, total suspended solids by 86%, Wetlandcare Mark Artificial wetland project - 1, 3 1, 2 PA0374 BALLINA, NSW, biological oxygen demand by Australia Bayley Camreay Holdings 2478. 48%, total phosphorus by 75%, total nitrogen by 85%, faecal coliforms by 93%. Outcomes of improved pasture cover by one cover category will Mary River be 22% reduction in suspended PA 0142, Catchment Brad PO Box 1027, Western Mary Subcatchments sediment emission to Hervey 1, 3 2 PA 0375 Coordinating Wedlock GYMPIE, 4570. Grazing Landscapes Project Bay. Hillslopes at risk are Wide Committee Bay Creek downstream of Kilkivan, and Glastonbury Creek. Outcomes from 40% of bank Mary River length stabilised in the Mary Catchment Brad PO Box 1027, MO5, M07, MO8 Rivercare Catchment will be 15% 1, 3 2, 3, 4, 7 PA0058 Coordinating Wedlock GYMPIE, 4570. Projects reduction in suspended Committee sediment emission to Hervey Bay. Banks at risk of erosion

108 are in Wide Bay Creek downstream of Kilkivan , and the upper sections of Glastonbury Creek.

109

110

5.6 UPPER MARY MANAGEMENT AREA

RESOURCE CONDITION TARGET FOR THE UPPER MARY RECEIVING WATERS (WORKING TITLE)

Sediment, nutrient, and herbicides delivered into freshwater receiving waters of the Upper Mary Management Area are stabilised and reduced by 2050.

ASPIRATIONAL TARGETS FOR THE UPPER MARY RECEIVING WATERS (WORKING TITLES)

1) Both diffuse and point source loads of sediment, nutrients and herbicides are consistent with the Environmental Values and Water Quality Objectives of the region. Region-wide standards and best management practices are widely used by 2015.

2) Concentrations of total nitrogen, ammonia, total phosphorus, filterable reactive phosphorus, and total suspended solids in the Upper Mary are closer to concentrations observed at local reference sites by 2015 (mg/L: lowland sections NH3 = 0.024, TN =0.473, TP = 0.046, FRP = 0.007, TSS = 8.56; headwater sections NH3 = 0.006, TN =0.17; TP = 0.017, FRP = 0.006; TSS = 1.18).

3) Greater than 75% of water supplied and used is managed by water use efficient practices across irrigation, urban, industrial and other uses by 2015.

4) 50% of priority riparian zones and sub-catchments (as identified by PAP2.2, the Lake Baroon Catchment Implementation Plan, and the Maleny Groundwater Investigation Group) are under Rivercare or Landcare works aimed at Water Quality outcomes by 2015.

MANAGEMENT ISSUES

1) Maintaining physical and chemical components of the Upper Mary receiving waters. In particular, better management of high total nitrogen contributions upstream of Pickering Bridge and Imbil. Also better management of total suspended solids, total phosphorus, and filterable reactive phosphorus contributions upstream of Pickering Bridge and Camboon Bridge. This includes stabilising bank erosion along the Mary River upstream of Gympie, in lower Amamoor Creek, in lower Kandanga Creek, and lower Yabba Creek. 2) Managing sediment generated by hill-slope erosion in Amamoor, Kandanga, and Yabba Creeks’ where there is presently weak soil stabilisation by deep-rooted vegetation, or disturbances caused by forestry operations.

111 3) Managing sediment and nutrient loads from identified stormwater risk zones. This includes strategies of land based disposal of dairy waste, and constructing off site watering points to keep cattle out of creeks. 4) Managing the interception of nutrients entering streams via groundwater seeps, resulting from loss of riparian buffer strips and poor management of septic tanks. 5) Managing poor shading and structural woody habitat cover resulting from loss of riparian vegetation. 6) Maintaining hydrological regimes in freshwater wetlands. 7) Maintaining the extent, condition, and diversity of habitat associated with freshwater wetlands.

112 EXISTING CAPACITY AND RECENT PROJECTS

Aspir- Manage- BMRG Lead Project ational ment Project Contact Project Title Project Outcomes Organisation Leader Target Issue Number

The project identified areas of poor Maryborough City Urban Stormwater Quality on a Kylie Council, PO Box sub-catchment basis, and made Maryborough City 1 3 PA0221 Matheson & 110, Marywise Urban Stormwater recommendations that each Cluster Council Amy Gosley MARYBOROUGH, Council (in the Mary LGAC) can do 4650 to improve Urban Stormwater quality. The project reviewed efficient Horticulture Communications programme to water use options available in Bundaberg Fruit House, 2 Maybe enhance water efficiency, water the horticulture, turf, cut flowers, 3 PA0331 & Vegetable Matt Dagun Tantitha St, 3, 6 & 7 security and environmental flow primary industries and urban Growers BUNDABERG, outcomes sectors. Community 4670 involvement. The main purpose of this activity Horticulture was to better understand Bundaberg Fruit House, 2 Integrated AreaWide sediment and nutrient 1, 2 1, 2, 3 PA0062 & Vegetable Matt Dagun Tantitha St, Management in diverse farming contributions to water quality Growers BUNDABERG, systems from horticultural farm practices 4670 in the region.

Design of a wetland to passively filter treated sewage to reduce PO Box 114, total suspended solids by 86%, Wetlandcare Mark Artificial wetland project - 1, 2 3 PA0374 BALLINA, NSW, biological oxygen demand by Australia Bayley Camreay Holdings 2478. 48%, total phosphorus by 75%, total nitrogen by 85%, faecal coliforms by 93%.

113 Outcomes from 40% of bank Mary River length stabilised in the Mary Catchment Brad PO Box 1027, MO5, M07, MO8 Rivercare Catchment will result in a 15% 1, 4 1, 4, 5 PA0058 Coordinating Wedlock GYMPIE, 4570. Projects reduction in suspended Committee sediment emission to Hervey Bay.

Installation of off-site watering points and exclusion of cattle from riparian zones with fencing. Identification of factors Qld limiting uptake of initiatives by Dairyfarmers 1, 2, 3, Raelene Competitive Tender Program – dairy farmers. Outcomes from 1, 3, 4 PA 0147 Organization 4 Rosevear East Gympie Dairy Group 14 bids represented a total and Subtropical reduction of 249,683 kg’s N OR Dairy 0.12% of total nitrogen emission to Hervey Bay. 39,498 kg’s of phosphorus OR 0.2% of total phosphorus emission to Hervey Bay.

Outcome was a groundwater model that describes stream PO Box 7081, SEQ Andrew Upper Obi Obi Groundwater recharge zones along Obi Obi 1, 2, 4 1, 3, 4 PA0154 SIPPY DOWNS, Catchments Ltd. Todd Monitoring Project Creek and associated nutrient 4556. transfer to streams from dairy pastures.

Development and implementation of Lake Baroon Catchment Management 1, 2, 3, Lake Baroon Murray PO Box 567, Lake Baroon Catchment Strategy and Country to Coast 1, 2, 4 PA0017 4, 5, 7 Catchment Care Dunstan MALENY, 4552. Supervisor Co-sponsored position targets. Outcomes of on-ground implementation will reduce suspended sediment emission from Obi Obi Creek by 29-43%,

114 total nitrogen by 20-31%, and total phosphorus by 19-33%.

115

116

CHAPTER 6 REASONABLE ASSURANCE STATEMENT

117

6.1 BACKGROUND

The Burnett Mary Regional Group and Wide Bay Water Corporation have an agreement with the Commonwealth of Australia, represented by the Dept of Environment, Water, Heritage and the Arts, to prepare the Water Quality Improvement Plan (WQIP) for the Mary Catchment. This project was initiated to enhance water quality planning and management processes, to improve water quality in the Mary river and its tributaries that presently experience poor or deteriorating water quality, as well as maintaining those parts of the river where water quality is currently good. The outcome is to establish a sound basis for investment to improve the condition of the receiving waters.

The following activities were conducted to address the delivery of nutrients, herbicides/pesticides, and suspended sediments loads into the river network and to the end of catchment, and to improve to water quality of these receiving waters at a system scale:

• Preparation of the Mary WQIP; • Development of a stakeholder consultation strategy in conjunction with the preparation of the WQIP; • Alignment of the WQIP with the Regional Integrated Natural Resource Management Plan.

This Reasonable Assurance Statement (RAS) addressed issues that require attention to give a high degree of confidence that WQIP targets will be achieved as a consequence of WQIP implementation. The RAS addresses the uncertainty associated with:

• knowledge of the response of the system to pollutant loads; • effectiveness of proposed interventions to achieve load reductions; and • adoption of proposed interventions, in terms of timing and extent.

6.1.1 Statement

The ability to meet targets associated with this Water Quality Improvement Plan (WQIP) requires applying sustainable growth principles that are supported by science, and a responsive monitoring and evaluation strategy that can supply new knowledge about the effectiveness of management approaches. Furthermore, development and implementation of management interventions to achieve the targets have to be underpinned by an adaptive management philosophy.

Monitoring will be used to quantify the effectiveness of the management actions described in Chapter 5, as well as to support better estimates of pollutant loads obtained by models. The plan can be updated to broaden effective management actions or revisit actions that were not effective.

118

Water quality monitoring programs in the region include state agency deliverables (to support sustainable water extraction from rivers, and water quality objectives of estuary receiving waters), and various State Investment Projects and the BMRG (to support WQIP and reef target objectives). The objectives of the water quality sampling programs, and a map showing the location of sampling points, are reported by the Queensland Government (http://www.regionalnrm.qld.gov.au/policies_plans_legislation/policies_strategi es/gbr_water_quality/monitoring_report/index.html).

Future monitoring and reporting programs need to be developed to effectively monitor the outcomes of this plan. This may be achieved by coordination of sampling schedules and data transfer among the existing monitoring programs.

6.1.2 Knowledge of the Response of the System to Pollutant Loads

Substantial modelling and monitoring input has been used to develop this plan, with the result that planning of improvements to pollutant loads from significant point sources (e.g. sewage treatment plants), landscape patches (e.g. irrigated horticulture, headwater basalts), and management actions (e.g. Rivercare, Landcare) can be identified and prioritised. There are however some knowledge gaps that need to be addressed to fully understand contributions to marine receiving waters from the Mary River.

A receiving model for marine waters needs to be developed to evaluate the attenuation of sediment, nutrients, and herbicides/pesticides within and out of Hervey Bay. The circulation dynamics of this important estuary are somewhat unusual, and this knowledge gap has been identified as a priority management action. This would probably need the involvement of one or more major partners such as CSIRO.

Also further research is needed to clarify the role of low base flows in estuary ecosystems, and particularly their involvement in the production of bait fish and other invertebrates, upon which fish feed. These species are required to attract and retain larger predatory fish species to the lower reaches of the estuary, upon which recreational anglers and the local economies they support in part rely. The provision of brackish water habitat at the head of the estuary is needed to provide migration cues for motile biota, ultimately awaiting large environmental flows. Compensatory flow releases from the Mary Barrage and upstream dams may be required to maintain quasi-natural flow inputs to the estuary.

119 6.1.3 Effectiveness of Proposed Interventions to Achieve Load Reductions and Improve Water Quality

Evaluation and reporting is critical for steering adaptive management, and enabling continuous improvements to land management to address end of catchment loads and concentrations. Monitoring needs to be done at various scales (spatial and temporal) across which improvements can be measured. Results need to be integrated, synthesised, and translated into applied knowledge to inform the end users (e.g. farmer, regional NRM group, government), enable strategic planning, and facilitate implementation across a the range of scales.

Baseline data for the Mary WQIP was developed with respect to concentrations of nutrients, suspended solids, herbicide and pesticides over a 1½ year period, with the intention of follow up monitoring when the landscape has been allowed to respond to improved land management. Some of the ambient data (nutrients, sediments, herbicides) have been presented in chapter 3 of this report, and the State of the Estuary study, which was used as a basis for aspirational targets. Events monitoring at sub-basin scale has also been successfully developed to support the Mary WQIP, and results can be used to obtain better estimates of pollutant loads and improve models.

The baseline investigation was designed as a nested hierarchy of sample points for ambient monitoring, to facilitate scale dependent assessments. Reach scale assessments (which monitor specific projects against a target reference condition) can be aggregated at sub-basin and basin scales (across the Mary Catchment), and if required also at the landuse scale (across the Burnett Mary region) to give a regional condition assessment. Event monitoring gives information about loads coming from the two key sub-basins in the Mary.

Effective data warehousing and information sharing are vital for the collaborative approach.

Reporting is required to allow diverse, and definitive evidence-based, findings from monitoring, investigations, test trialling, and modelling to support education outcomes.

The whole process is interactive and needs to be refined with time. However reporting and adaptive management of the plan will be consistent with BMRG’s reporting program for Country to Coast – a healthy sustainable future.

ANNUAL REVIEWS

120 Annual performance reviews reporting implementation progress are proposed to be completed by BMRG with key stakeholders including State Government and Industry Groups invited to attend.

PHASE 2 IMPLEMENTATION

After completion of the priority management actions and establishment of pollution targets, the plan will need to be updated in light of new findings.

The process will involve consultation, and a review with cost analysis of management actions. The next version of the Mary Catchment WQIP will be drafted and ready for implementation.

6.1.4 Adoption of Proposed Interventions, in terms of Timing and Extent.

The first stage of consultation and review to finalise the Mary Catchment WQIP requires meetings with both science and stakeholder groups to evaluate the science that contributed to the report, review priority pollutants with respect to source, establish resource condition targets for end of catchment loads, and finalise aspirational targets.

The suggested approach for the second stage of consultation, to expose this draft Mary Water Quality Improvement Plan to a larger proportion of key stakeholders and the public, is to conduct a catchment crawl information day. This includes a catchment crawl down the catchment from the Obi Obi Creek headwaters, to River Heads as an information session. The draft plan will be formally presented to stakeholders, to seek input from stakeholders with respect to their involvement with the plan and delivery timelines.

After a review period has elapsed, further presentations will be given to stakeholder groups on request (following the catchment crawl), and submissions will be considered for a further workshop to finalise the plan.

Targeted stakeholder groups for the Catchment Crawl Information Day are suggested to be:

• Agforce • Aquagen • Barung Landcare • Burnett Mary Regional Group for Natural Resource Management • Fraser Coast Regional Council • Fraser Coast Representatives of the Regional Seafood Association • Fraser Coast Sunfish • Fraser Island Defenders Organisation

121 • Growcom • Gympie and District Beef Liaison Group • Gympie Landcare • Gympie Regional Council • Lake Baroon Catchment Care Group • Lower Mary Landcare • Mary River Marina • Maryborough Canegrowers • Queensland Environmental Protection Agency • Queensland Dairyfarmers Organisation • Queensland Department of Natural Resources and Water • Queensland Department of Primary Industries and Fisheries • Queensland Water Infrastructure • Subtropical Dairy • Sunshine Coast Regional Council • Sunwater • The Mary River Catchment Coordinating Committee • The BMRG Traditional Owner Working Group • The Coastal Water Quality Alliance • Tiaro Landcare • Wildlife Preservation Society • Wide Bay Burnett Conservation Council • Wide Bay Water Corporation • Wide Bay Burnett Regional Coordinating Group

122

APPENDICES 1 & 2

Draft Version 1.2 December 2008

1.1 APPENDIX 1: CONCEPTUAL MODELS FOR PRESSURE/DRIVER – VECTOR – CONDITION IN THE MARY CATCHMENT

Mary River Estuary Section: 6.0km from the river-mouth

Temperature Discharge (m3.s-1) (oC) Driver

Conductivity (µµµScm-1 at 25oC)

pH

Turbidity (NTU) Vector

Dissolved Oxygen Light Penetration (m) (% saturation)

Chlorophyll-a (µµµg/L) Condition

Figure 1: Conceptual model of driver/pressure – vector – condition in the Mary River Estuary, 6.0km site. Line thickness relates directly with the strength of correlation between the indicators and their dependent variables.

Turbidity = 6.07±0.52 - 0.07±0.01[Conductivity]. This relationship covers 22% of the measured variation in turbidity as being dependent on conductivity. There was no significant relationship with discharge and the Southern Oscillation Index in the stepwise multiple regression.

Log [Chl_a] = 0.013±0.006[Temperature] - 0.495±0.075 log[Light penetration] - 0.033±0.136. This relationship covers 26% of the measured variation in turbidity as being dependent on temperature and light penetration.

[Dissolved Oxygen] = 103.28±3.269 - 0.424±0.140[Temperature] – 3.487±1.715 log[Chl_a]. This relationship covers 10% of the measured variation in dissolved oxygen as being dependent on temperature and chlorophyll-a concentration.

Mary Catchment Water Quality Improvement Plan - i -

Mary River Estuary Section: 22.5km from the river-mouth

Discharge (m3.s-1) Driver Tidal difference (m) Conductivity (µµµScm-1 at 25oC)

Organic N TP Turbidity (NTU) TN (mg/L) (mg/L) (mg/L) Vector FRP Dissolved Oxygen pH Light Penetration (m) NOx (mg/L) NH3 (mg/L) (mg/L) (% saturation)

Chlorophyll-a (µµµg/L)

Condition Figure 2: Conceptual model of driver/pressure – vector – condition in the Mary River Estuary, 22.5km site. Line thickness relates directly with the strength of correlation between the indicators and their dependent variables.

Ln[Turbidity] = 9.183±2.226 - 0.026±0.004[Conductivity] – 2.091±0.964[Tidal Difference]. This relationship covers 21% of the measured variation in turbidity as being dependent on conductivity and the average monthly tidal range. There was no significant relationship with the Southern Oscillation Index in the stepwise multiple regression.

[TN] = 0.18±0.02.log[Discharge] + 0.61±0.02. This relationship covers 33% of the measured variation in total nitrogen as being dependent on discharge. There was no significant relationship with the Southern Oscillation Index in the stepwise multiple regression.

Ln[Organic N] = 0.37±0.04.log[Discharge] - 1.33±0.04. This relationship covers 35% of the measured variation in organic nitrogen as being dependent on discharge. As with total nitrogen was no significant relationship with the Southern Oscillation Index.

Ln[TP] = 0.35±0.05.log[Discharge] – 2.89±0.05. This relationship covers 27% of the measured variation in total phosphorus as being dependent on discharge.

Mary Catchment Water Quality Improvement Plan - ii -

Mary River Estuary Section: 36.1km from the river-mouth

Discharge (m3.s-1) Temperature (oC)

Driver Tidal difference (m) Conductivity (µµµScm-1 at 25oC)

Turbidity (NTU) Vector

Light Penetration (m) Dissolved Oxygen

pH

Chlorophyll-a (µµµg/L) Condition

Figure 3: Conceptual model of driver/pressure – vector – condition in the Mary River Estuary, 36.1km site. Line thickness relates directly with the strength of correlation between the indicators and their dependent variables.

Log[Turbidity] = 5.12±1.05 - 0.04±0.02.ln[Conductivity] – 1.41±0.46.[Tidal Difference]. This relationship covers 9% of the measured variation in turbidity as being dependent on conductivity and the average monthly tidal range. There was no significant relationship with the Southern Oscillation Index in the stepwise multiple regression.

Ln[Chl_a] = 2.11±0.43 Lightpenetration + 0.02±0.23. This relationship covers 13% of the measured variation in turbidity as being dependent on light penetration (secchi depth), with no significant relationship being measured for temperature.

Ln[Dissolved Oxygen] = 4.769±0.063 - 0.021±0.003.[Temperature] + 0.062±0.010.ln[Chl_a]. This relationship covers 39% of the measured variation in dissolved oxygen as being dependent on temperature and chlorophyll-a concentration.

Mary Catchment Water Quality Improvement Plan - iii -

Mary River Estuary Section: 56.7km from the river-mouth

Discharge (m3.s-1) Temperature Driver (oC)

Conductivity Organic N TP Turbidity (NTU) TN (mg/L) (µµµScm-1 at 25oC) (mg/L) (mg/L)

FRP Vector Light Penetration (m) NOx (mg/L) NH3 (mg/L) (mg/L)

pH Dissolved Oxygen Chlorophyll-a (µµµg/L)

Condition Figure 4: Conceptual model of driver/pressure – vector – condition in the Mary River Estuary, 56.7km site. Line thickness relates directly with the strength of correlation between the indicators and their dependent variables.

Turbidity = 0.88±0.22.Log.[Discharge] + 3.69±0.22. This relationship covers 10% of the measured variation in turbidity as being dependent on discharge. The stepwise multiple regression indicated no significant relationship with the monthly tidal range or the Southern Oscillation Index.

Ln.[TN] = 0.25±0.03.log[Discharge] - 0.82±0.03. This relationship covers 27% of the measured variation in total nitrogen as being dependent on discharge. There was no significant relationship with the Southern Oscillation Index in the stepwise multiple regression.

Ln[Organic N] = 0.17±0.03.log[Discharge] - 1.04±0.03. This relationship covers 17% of the measured variation in organic nitrogen as being dependent on discharge. As with total nitrogen was no significant relationship with the Southern Oscillation Index.

TP = 0.030±0.005.log[Discharge] + 0.213±0.005. This relationship covers 17% of the measured variation in total phosphorus as being dependent on discharge.

Ln[Chl_a] = 0.09±0.02[Temperature] – 4.60±0.85.ln[NH3] + 0.14±0.39. This relationship covers 25% of the measured variation in chlorophyll-a as being dependent on temperature and ammonia concentrations, with no significant relationship being measured for filterable reactive phosphorus, oxides of nitrogen, or light penetration.

Mary Catchment Water Quality Improvement Plan - iv -

Lower Mary River Section: 91.0km from the river-mouth

Discharge (m3.s-1)

Driver Temperature (oC)

Organic N TP Turbidity (NTU) TN (mg/L) (mg/L) (mg/L)

FRP Vector NOx (mg/L) NH3 (mg/L) (mg/L)

Chlorophyll-a (µµµg/L) Condition

Figure 5: Conceptual model of driver/pressure – vector – condition in the Lower Mary River, 91.0km site. Line thickness relates directly with the strength of correlation between the indicators and their dependent variables.

Turbidity = 0.28±0.08.Log100[Discharge] + 0.43±0.04. This relationship covers 11% of the measured variation in turbidity as being dependent on discharge. The stepwise multiple regression indicated no significant relationship with the Southern Oscillation Index.

Ln.[TN] = 0.75±0.09.Log100[Discharge] – 1.12±0.05. This relationship covers 39% of the measured variation in total nitrogen as being dependent on discharge.

Ln[Organic N] = 0.40±0.10.Log100[Discharge] - 1.17±0.05. This relationship covers 13% of the measured variation in organic nitrogen as being dependent on discharge.

Log100TP= 0.14±0.03.log100[Discharge] - 0.72±0.01. This relationship covers 24% of the measured variation in total phosphorus as being dependent on discharge.

Ln[Chl_a] = 0.08±0.02[Temperature] – 3.29±0.71[NOx] + 0.89±0.25[Turbidity] - 0.77±0.44. This relationship covers 38% of the measured variation in chlorophyll-a as being dependent on temperature and NOx concentrations, with no significant relationship being measured for filterable reactive phosphorus, oxides of nitrogen, or light penetration.

Mary Catchment Water Quality Improvement Plan - v -

Lower Mary River Section: 170.4km from the river-mouth

Discharge (m3.s-1) Driver

Turbidity TN Organic N TP (mg/L) (NTU) (mg/L) (mg/L)

NOx FRP

Vector (mg/L) NH3 (mg/L) (mg/L)

Chlorophyll-a (µµµg/L) Condition

Figure 6: Conceptual model of driver/pressure – vector – condition in the Lower Mary River, 170.4km site. Line thickness relates directly with the strength of correlation between the indicators and their dependent variables.

Turbidity = 2.3±0.3.Log100[Discharge] + 2.2±0.2. This relationship covers 31% of the measured variation in turbidity as being dependent on discharge. The stepwise multiple regression indicated no significant relationship with the Southern Oscillation Index.

Ln[TP] = -0.96±0.13.Log100[Discharge] - 1.76±0.07. This relationship covers 34% of the measured variation in total phosphorus as being dependent on discharge. There was no significant relationship with the Southern Oscillation Index in the stepwise multiple regression.

Log[Chl_a] = 1.4±0.3 FRP – 1.9±0.5 NH3 + 0.4±0.1. This relationship covers 21% of the measured variation in chlorophyll-a as being dependent on filterable reactive phosphorus and ammonia concentrations, with no significant relationship being measured for temperature, turbidity or concentrations of oxides of nitrogen.

Mary Catchment Water Quality Improvement Plan - vi -

Upper Mary River Section: 244.1 km from the river-mouth

Discharge (m3.s-1) Driver Temperature (oC)

Turbidity TN Organic N TP (mg/L) (NTU) (mg/L) (mg/L)

NOx FRP

Vector (mg/L) NH3 (mg/L) (mg/L)

Chlorophyll-a (µµµg/L) Condition

Figure 7: Conceptual model of driver/pressure – vector – condition in the Lower Mary River, 244.1km site. Line thickness relates directly with the strength of correlation between the indicators and their dependent variables.

Turbidity = 0.39±0.6Ln.[Discharge] + 2.13±0.11. This relationship covers 27% of the measured variation in turbidity as being dependent on discharge. The stepwise multiple regression indicated no significant relationship with the Southern Oscillation Index.

Log100[TN] = 0.026±0.005.Ln[Discharge] – 0.266±0.009. This relationship covers 21% of the measured variation in total nitrogen as being dependent on discharge.

Organic N = 0.011±0.005.Ln[Discharge] + 0.244±0.009. This relationship covers 4% of the measured variation in organic nitrogen as being dependent on discharge.

Ln[TP] = 0.084±0.024.Ln[Discharge] – 3.42±0.04. This relationship covers 11% of the measured variation in total phosphorus as being dependent on discharge. There was some evidence for serial correlation of the time series data, which means that the validity of the statistical relationship between phosphorus and discharge may be overemphased.

Ln[Chl_a] = 0.11±0.02[Temperature] – 12.8±2.3 FRP – 43.3±15.2 NH3 + 0.28±0.05 Turbidity - 0.36±0.41. This relationship covers 40% of the measured variation in chlorophyll-a as being dependent on filterable reactive phosphorus and ammonium concentrations, as well as turbidity and temperature.

Mary Catchment Water Quality Improvement Plan - vii -

1.2 APPENDIX 2: MANAGING EXISTING WATER QUALITY

2.1 GOALS

2.1.1 To ensure that a water supply for all users of water within the Mary catchment which is of good quality and ecologically and socially sustainable

2.2 OBJECTIVES

2.2.1 To ensure a water supply for all users which is economically, ecologically and socially sustainable 2.2.2 To ensure that the speed and volume of catchment run off from the catchment more closely resembles the “natural” state

2.3 STRATEGIES

2.3.1 Use existing developed water supplies as efficiently as possible 2.3.2 Establish and transfer available information on water resources 2.3.3 Stimulate community discussion on population issues and water consumption 2.3.4 Lift awareness and understanding of water and wastewater management 2.3.5 Develop management techniques for streams within the catchment which are stressed through uncontrolled demands for water

Action By whom By when

Promote potable reuse schemes, grey water recycling, rainwater WaterA’s ongoing tanks, metering, leak detection programs, dual reticulation and user LGA.s pay pricing for both urban and rural supplies particularly in SE DNRW Queensland Foster water harvesting in high flow periods in preference to weir BMRG ongoing impoundments on the Mary and its Tributaries DNRW LGAs Install meters for irrigators and establish levels of use for rural licence WaterA’s ongoing holders on regulated and non regulated streams DNRW Review and improve water release methodology and monitoring from WaterA’s 2010 impoundments particularly dams. New dams to have multilevel DNRW ongoing offtakes incorporated into design. Retrofitting to existing situations. Inform LGAs and the community of water availability within the DNRW 3 yearly catchment Regularly conduct audits of rural residential surface and ground water DNRW 3 yearly use and management for impacts on water availability and widely distribute the results to the community and LGAs Conduct a study into the relationship between impoundments and the BMRG Commence riverine, estuarine and marine environments of the Mary and the DNRW 2010 Great Sandy Marine Park EPA QWI Science Provider Where a weir water storage requires replacement or refurbishment Qld Govt From 2010 replacement with off stream storage facility is to be seriously LGAs considered and the weir storage removed

Mary Catchment Water Quality Improvement Plan - viii -

Develop industry based BMPs to reduce pollution from agricultural AG Ongoing sources and review existing industries Review Progress 2010 Educate on the relationship between water supply and wastewater DNRW ASAP treatment

3 IMPROVING WATER QUALITY

3.1 GOALS

3.1.1 Sediment, nutrient, and herbicides delivered to receiving waters of the Mary Catchment are stabilised and reduced by 2050.

3.2 OBJECTIVES

3.2.1 To continuously improve water quality within the catchment within the limits of practicality 3.2.2 To ensure that all water users put back water quality of a comparable quality that they take out 3.2.3 To ensure that long term continued funding is available for water quality improvement works

3.3 STRATEGIES

3.1 Establish credible information on water quality within the catchment, past and present as a basis for decision making 3.2 Raise the profile of water quality with Government, NRM bodies and the Community 3.3 Eliminate the impact of sewage pollution (emphasis on STPs) 3.4 Implement measures to reduce the pollutant loads from urban stormwater runoff 3.5 Implement measures to reduce the pollutant loads from sand/gravel extraction and mining activities 3.6 Implement measures to reduce the pollutant loads from weirs on the Mary and its tributaries 3.7 Identify diffuse sources of pollution in the catchment 3.8 Reduce diffuse sources of pollution in the catchment 3.9 Establish financial security for actions 3.10 Establish expertise to implement actions

STRATEGY 3.1 Establish credible information on water quality within the catchment, past and present as a basis for decision making.

Action By By when whom Support the continued funding of the catchment based water quality DNRW Established monitoring program which presently provides both ambient and event EPA based (flood) based data BMRG CWQA MRCCC QWI LBCCG Collect and interpret data on water quality (which distinguishes between As ongoing natural and human induced sources of poor water quality) to identify above current status, changes and trends

Mary Catchment Water Quality Improvement Plan - ix -

Determine the impact on the marine environment of waters from the Mary EPA ASAP catchment, including impact on commercial fisheries and recreational DNRW industries QDPI BMRG QWI

STRATEGY 3.2 Raise the profile of water quality with Government, NRM bodies and the Community

Action By By when whom Continue to support CWQA, Landcare and waterwatch community BMRG ongoing groups Hold a technical water quality forum which focuses on water quality BMRG 3 yearly first and its improvement in the catchment EPA 2009 DNRW Provide meaningful incentives and penalties to encourage elimination LGA’s ongoing of discharges EPA Promote the concept of zero discharge of pollutants to waterways from LGAs ongoing point sources MRCCC EPA Provide 5 yearly pollution statements and maps of the catchment to EPA ongoing community groups DNRW

STRATEGY 3.3 Eliminate the impact of sewage pollution (emphasis on STPs)

Action By By whom when Progressively up grade all STPs in the catchment to include tertiary treatment Q/Gov 2010 (nutrient removal) and effluent reuse to ensure all point source pollution EPA sources to receiving waters meet EPA guidelines LGAs Encourage the development of legislation which discourages any point Q/Gov 2015 source release to receiving waters EPA Implement a fight phosphorus campaign to reduce inputs to STP’s BMRG ASAP LGAs EPA DNRW Encourage LGAs to inspect and manage septic systems within the Mary BMRG 2010 catchment EPA Develop a sewage effluent control education and information package for EPA 2010 small communities LGAs Eliminate illegal connections to the sewage system particularly stormwater LGAs Ongoing Reduce trade waste from urban sewage systems and promote trade waste EPA Ongoing controls and reuse LGAs Implement potable reuse, dual reticulation and land disposal as appropriate EPA Ongoing LGAs Develop procedures for use of sludge rather than as land disposal LGAs ASAP EPA Encourage better management of reuse systems which have better capacity LGAs ASAP to cope with rainfall events EPA

Mary Catchment Water Quality Improvement Plan - x -

Encourage dry compositing toilet systems rather than septics LGAs ASAP EPA Educate on the relationship between water supply and waste water and the DNRW ASAP need to link their funding

STRATEGY 3.4 Implement measures to reduce the pollutant loads from urban stormwater runoff

Action By By whom when Develop and implement urban runoff control plans for all towns and BMP DHLGP 2010 guidelines for the catchment LGAs EPA BMRG Encourage urban runoff control measures into new and existing areas prior to LGAs ongoing discharge into waterways eg discharge via retention ponds and or artificial EPA wetlands stocked with native macrophytes Undertake education campaign to highlight the impacts of urban stormwater EPA 2010 pollution in the Mary and possible solutions LGAs BMRG Lift compliance with urban runoff and stormwater legislation, eg by laws and EPA ASAP incentives LGAs Involve community groups in determination and management of urban BMRG ongoing stormwater runoff and artificial wetland construction Encourage storm water harvesting as both a raw water source and for some EPA ongoing treatment in reuse schemes when normal supplies are low eg watering of LGAs council parks and dust control

STRATEGY 3.5 Implement measures to reduce the pollutant loads from sand/gravel extraction and mining activities

Action By By whom when Develop and implement urban runoff control plans for all towns and BMP DHLGP 2010 guidelines for the catchment LGAs EPA BMRG

STRATEGY 3.6 Implement measures to reduce the pollutant loads from weirs on the Mary and its tributaries

Action By By whom when Investigate, as required, the replacement of weirs from the Mary and its DNRW 2010 tributaries with off stream storages

STRATEGY 3.7 Identify diffuse sources of pollution in the catchment

Action By By whom when

Mary Catchment Water Quality Improvement Plan - xi -

Conduct water quality studies for all water storages within the catchment and BMRG 2010 develop Water Quality Management Strategies for each including for EPA environmental and event releases DNRW Conduct water quality modelling studies within the Mary catchment pertaining BMRG 2010 to diffuse pollutant supply DNRW QDPI Apply decision support package to land use map of Mary and determine BMRG 2010 sources of nutrients DNRW QDPI Involve community groups in determination of diffuse point sources BMRG ongoing

STRATEGY 3.8 Reduce diffuse sources of pollution in the catchment

Action By whom By when

Implement water quality strategies for water supply impoundments Dam 2010 managers Reduce stock access (especially cattle and horses) to streams, dams and Qld Govt Ongoing rivers to reduce sediment and nutrients reaching waterways and damage LGAs to banks and riparian vegetation including the introduction of offstream Ag stock watering points Industry Continue improvements in managing runoff from forestry plantations QDPI ongoing Forestcom EPA Reduce contamination of surface and ground water in the catchment DME ongoing from mining activities and implement rehabilitation measures EPA 2.8.5 Improve road design and construction on hydrology and water Qld Govt From quality in particular from runoff, bridges and culverts with allowance for LGAs 2010 biopassage Where road, bridge, ford or culverts require replacement or refurbishment Qld Govt From appropriate sediment/erosion control are to be incorporated into contracts LGAs 2010 and audited Where a weir water storage requires replacement or refurbishment Qld Govt From replacement with off stream storage facility is to be seriously considered LGAs 2010 and the weir storage removed Review Native Forrest and Plantation Management Code and Agricultural AG Ongoing Codes of Practice to ensure the meet BMP with respect to riparian buffer industries Review widths and forestry track construction and harvesting in steep unstable Qld Govt Progress areas and audit practices to ensure compliance LGAs 2010 Encourage widespread adoption of QDOs dairy effluent control guidelines QDO 2010 BMRG QDPI Agforce Provide incentives to primary producers to upgrade equipment and BMRG Ongoing techniques to ensure that all waste waters are reused in a sustainable Qld Govt Review manner to minimise nutrients entering streams and rivers Q DPI&F Progress 2010 Review licence conditions and riparian rights in unregulated tributaries to DNRW 2010 reduce dissolved oxygen and salinity problems that may relate from abstraction

Mary Catchment Water Quality Improvement Plan - xii -

Review and audit recreational vehicle (4WDs and motor cycles) use Qld Govt 2010 within the catchment, particularly in steeper areas to reduce sediment LGAs reaching streams and rivers Q Trans Review and audit recreational and professional boat usage with streams, Qld Govt 2010 rivers, weirs and impoundments to reduce damage to banks and LGAs sediment Q Trans

STRATEGY 3.9 Establish financial security for actions

Action By whom By when Establish a WQIP levy for the Mary River Catchment of 1c per kilolitre to be Qld 2010 collected by appropriate Water Authority and paid directly to the Mary Govt Catchment WQIP and Management Trust Fund (Funds to be used for Water community Catchment and Landcare activities appropriate to WQIP, Authorities riparian restoration, other WQIPO works and to support WQIP Co-ordinator LGAs

Mary Catchment Water Quality Improvement Plan - xiii -

STRATEGY 3. 10 Establish expertise to implement actions

Action By whom By when Establish a WQIP Co-ordinator for the Mary River Catchment funded from Qld 2010 the Mary Catchment WQIP and Management Trust Fund to co-ordinate Govt community Catchment and Landcare activities appropriate to WQIP, Water riparian restoration, other WQIPO works and evaluate and report on WQIP Authorities and WQ improvement LGAs

Mary Catchment Water Quality Improvement Plan - xiv -

4 POTENTIAL BENEFITS AND DRAWBACKS OF MANAGEMENT STRATEGIES

STP upgrade

Potential benefits Potential drawbacks Mitigates water quality deterioration

Stock control

Potential benefits Potential drawbacks Mitigates water quality deterioration Need to develop alternative weed growth and fire risk/control in the riparian zone if Mitigates the aggravating factor of stock are totally excluded (potentially this riparian loss can be overcome with controlled grazing)

Facilitates natural vegetation

Point source controls

Potential benefits Potential drawbacks Improved water quality Cost of upgrading treatment processes

Improved habitat conditions Difficulties of compliance for small industries and landholders (economics, Possible economic benefits through capacity/knowledge and expertise increased efficiency of resource use (eg water and fertiliser)

Multilevel offtakes for dams

Potential benefits Potential drawbacks Improved water quality – closer Cost of refitting simulation of natural temperature variation, avoidance of low dissolved Requires efficient monitoring and oxygen inputs, avoidance of low adaptive management dissolved oxygen inputs, avoidance of heavy metals

Improved habitat conditions

Urban stormwater quality management

Potential benefits Potential drawbacks Improved water quality – reduced Cost toxicants (eg metals and hydrocarbons), nutrients, litter and sediment Will not succeed without a properly co- ordinated approach Improved habitat conditions

Mary Catchment Water Quality Improvement Plan - xv -

Possible economic benefits through increased efficiency of water use

Review and adjust monitoring programs

Potential benefits Potential drawbacks Enables proper targeting of problems, effective and efficient use of resources and evaluation of effectiveness of water quality improvement planning and implementation on a catchment and reach basis

Revegetation

Potential benefits Potential drawbacks Restoration of riparian habitat Cost

Benefits for water quality, instream Increased weeds, pest animals and fire habitat, bank stability, recreational risk opportunities, aesthetics, landscape values, stock shelter Loss of land from productive use

Improved property values Unlikely to be suitable as stand alone measure, for the following reason: Contributes to bank stability by protecting the surface from rainfall, deflecting and • Difficult to establish vegetation or reducing the velocity of near bank river undercut bank without using an flow) if species are appropriate and ecological succession of fast suitably placed and binding by roots growing species being gradually replaced by slow growing Has the added benefit of improving species. Vegetation at top of a habitat condition high bank does nothing to protect the exposed vertical surface of Roots assist in binding bank materials the bank, hence it is necessary to and stabilising moisture levels in banks establish trees at the toes of rotational slumps to provide root mats that stabilise. It is expected that the first 5 rows of trees will be fall into the river (and create structural woody habitat suitable for cod).

Riparian buffer zones

Potential benefits Potential drawbacks Shade Increased hydraulic resistance to flood flows with corresponding in channel flood Assist in bank stabilisation levels

Mary Catchment Water Quality Improvement Plan - xvi -

Riparian buffer zones limit input of Problematic in high energy areas due to catchment derived nutrients and scour pollutants Loss of significant areas of land from productive use

Protect existing remnants

Potential benefits Potential drawbacks Protects existing habitat values

Maintains local indigenous seed stocks

Protection less expensive than restoration – a most cost effective riparian management tool

Re-establish riparian canopy cover

Potential benefits Potential drawbacks Minimises need for use of herbicides Not effective for shade tolerant species

Additional benefit of restoring shade over Potential difficulty of re-establishing waterway canopy cover, especially in areas with dense weed understorey

Sub-catchment controls

Potential benefits Potential drawbacks Improved water quality in terms of Potential loss of land from productive use reduced suspended sediment, pesticides, herbicides and fertilisers Cost

Improved habitat conditions Will not succeed without a properly co- ordinated approach Diffuse source pollutants are a major pollutant source in the Mary Catchment Measurable benefits only accrue over the long term

Lower weir pool level (operate at a lower level)

Potential benefits Potential drawbacks Mitigates an aggravating factor of bank Reduced water storage capacity in erosion pondage is likely to have economic implications Effectively mitigates the impact of boat wash on river banks as boat traffic and Reduced recreational opportunities speed would be limited by the lower water levels Unlikely to be effective as a stand alone measure

Mary Catchment Water Quality Improvement Plan - xvii -

Reduced ponding and sedimentation In the lower reaches of tributaries Would not reinstate natural tidal regime – uncertain ecological implications Increased turnover of water in pondage as the storage volume is reduced High risk of weed invasion in re-exposed areas Exhumation of natural tidal pool-riffle sequences previously drowned by Greater temperature variations in barrage pondage and potential for greater aquatic vegetation growth in shallower water leading to dissolved oxygen depletion at night

High cost of retrofitting barrage to prevent tidal penetration

Cost of upgrading pumping facilities to maintain yield at lower operating level ( also potential need for an additional storage to make up for loss of storage capacity due to lower operating level

Land use planning to minimise risks to assets

Potential benefits Potential drawbacks Prevents conflict between river process Does not reduce or mitigate unnaturally and assets accelerated rates of lateral movement

No impedance to natural geo- morphological and ecological processes

Effective regardless of the cause of lateral movement

Asset relocation

Potential benefits Potential drawbacks Removes conflict between river Natural assets such as remnant riparian processes and assets without requiring vegetation and high value habitats intervention in the river channel generally cannot be feasibly relocated

No impedance to natural geo- Potential high economic/social cost of morphological and ecological processes asset relocation

Effective regardless of the cause of Does not reduce or mitigate unnaturally lateral movement accelerated rates of lateral movement

Structural bank protection works

Potential benefits Potential drawbacks Effective for halting bank erosion in key High initial capital outlay areas to protect high value assets

Mary Catchment Water Quality Improvement Plan - xviii -

(including high value remnant vegetation, Ongoing need for maintenance of works habitats or infrastructure) (particularly if the cause of accelerated bank erosion is not addressed) Effective stand alone measure for most types of bank erosion May cause or exacerbate erosion of other sections of the bank as erosive forces are not reduced but merely deflected to other locations

Effective bank reinforcement works effectively channelize a river/stream leading to loss of natural geomorphological and habitat characteristics (eg bank undercuts)

Aesthetic impacts

Bed stabilisation

Potential benefits Potential drawbacks Unlikely to be relevant to to major streams in the Mary River catchment, as bed erosion is generally not a significant cause of bank erosion

Bar management

Potential benefits Potential drawbacks Alleviates erosive forces on opposite Local in-stream disturbance by bank machinery, including impacts on water quality and habitat Can increase the effectiveness of bank reinforcement Increased erosion risk if there is excessive sediment removal from the channel

Prevent/cease sand gravel extraction

Potential benefits Potential drawbacks Prevents/removes a causal factor of Possible economic costs from the need erosion to obtain a greater proportion of sand and gravel from an alternative supply Enables natural regeneration and recovery processes to proceed Not necessarily effective as a stand alone measure Prevents further impacts on water quality and riverine life

Reduces the risk of future accelerated bank erosion

Boat use management

Mary Catchment Water Quality Improvement Plan - xix -

Potential benefits Potential drawbacks Mitigates an aggravating factor of bank Social/economic impacts arising from erosion change in recreational opportunities

Likely ancillary benefits for wildlife from Unlikely to be effective as a stand alone reduced noise and disturbance measure

Better immediate fish catches may result

Riparian weed control

Potential benefits Potential drawbacks Protects remnant riparian habitat Cost

Assists regeneration Difficulty of effective eradication of some weeds Improves effectiveness of revegetation Potential for pollution of waterway by Reduced fire risk and pest animals herbicides habitat

Aquatic weed control

Potential benefits Potential drawbacks Protects/restores aquatic habitat Potential for pollution of waterway by herbicides Maintains channel conveyance

Feral pig control

Potential benefits Potential drawbacks Protection of side stream vegetation, Logistical problems with shooting pigs water quality, bank condition Ecological problems such as impacts of Reduction of impacts on agricultural land baiting programs on non target species

Mary Catchment Water Quality Improvement Plan - xx -

References

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PERSONAL COMMUNICATIONS

• Banti Fenti. Senior Scientist, Queensland Natural Resources and Water. Performed SedNet modeling of the Mary Catchment in 2006, as a Water Quality State Investment Project deliverable.

• Gordon Cottle. Project coordinator of the Great Sandy Strait seagrass watch and monitoring program.

• Colin Limpus. Principal Scientist, Queensland Parks and Wildlife Service.

• Mike Ronan. Manager (Wetlands Policy, Natural Resources, Strategy and Policy), Queensland Environmental Protection Agency.

• Steve Burgess. Mary River Catchment Coordinating Committee.

• Tim Thornton. Friends of the Burrum River System Group.

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