Status of Groundwater Quality in the Cockburn Sound Catchment Final Report to Cockburn Sound Management Council M. G. Trefry, G. B. Davis, C. D. Johnston, A. G. Gardiner, D. W. Pollock and A. J. Smith February 2006 © 2006 CSIRO To the extent permitted by law, all rights are reserved and no part of this publication covered by copyright may be reproduced or copied in any form or by any means except with the written permission of CSIRO. Important Disclaimer: CSIRO advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it. Cover Photograph: From CSIRO Land and Water Image Gallery: www.clw.csiro.au/ImageGallery/ File: PSD_IND001_015.jpg Description: Heavy industry has operated in Cockburn Sound for 50 years. Aerial view of refinery and bulk cargo loading complex at Kwinana, WA. 1975. Photographer: Willem van Aken © 2006 CSIRO Contact Person: Mike Trefry CSIRO Land and Water Private Bag No. 5 Wembley WA 6913 Australia Ph: +61-8-9333 6286 Fax: +61-8-9333 6211 Email: [email protected] Web: http://www.clw.csiro.au/Staff/TrefryM/ Status of Groundwater Quality in the Cockburn Sound Catchment Status of Groundwater Quality in the Cockburn Sound Catchment Final Report to Cockburn Sound Management Council M. G. Trefry, G. B. Davis, C. D. Johnston, A. G. Gardiner, D. W. Pollock and A. J. Smith CSIRO Land and Water February 2006 i Preface The coastal resources of the Perth metropolitan area essentially define the lifestyle and culture of the majority of the population of Western Australia. Cockburn Sound is an iconic feature of this lifestyle, supporting a rich variety of commercial, industrial, defence, tourism and recreational uses for the broader community. However, the pressures on Cockburn Sound associated with urbanization and industrialization are increasing, and the local ecosystem is under stress. Recognizing this, the WA Government has established a regulatory and policy framework for managing the environmental values of Cockburn Sound. The Cockburn Sound Management Council (CSMC), established under the aegis of the WA Department of Environment, is charged with coordinating environmental management and planning to protect Cockburn Sound and its catchment. The coordination role is essential in managing such a complex system. Already CSMC has developed an Environmental Management Plan and brokered agreements between Local Government Authorities, planners and environmental regulators. The present groundwater contamination study is commissioned by CSMC to report on the environmental state of the Cockburn Sound system. This and other studies will inform CSMC on the current environmental performance of the Cockburn Sound system. With respect to the present groundwater study, key tasks are to identify important groundwater contamination threats to the amenity and environmental quality of the Sound, to identify gaps in management performance and to recommend potential improvements in future management practice. To this end, the study has concentrated on a summary review of literature and data pertaining to groundwater quality in the Cockburn Sound catchment and related literature on land-use impacts on groundwater. The literature and data was freely contributed to the study by a range of industry, government and community groups and associations, allowing a reasonably complete assessment of the important groundwater quality issues in the catchment. That some management gaps are identified in this study is no particular criticism of the environmental regulators, planners or industry – the catchment itself is developing rapidly in terms of urbanization, land use change and major planning initiatives. In such a dynamic context it is normal to review and update management practices regularly. However, it is important to understand that the capacity of any ecosystem to absorb stress is finite. Cockburn Sound itself is already under significant stress, so future planning for the Sound and its catchment must seek to balance the goals of economic and social development against environmental imperatives. This requires a greater level of consultation and cooperation between catchment stakeholders, and also requires advances in the scientific understanding of ecosystem processes in Cockburn Sound. Already a spirit of positive cooperation between major industry and CSMC is apparent, especially those companies sited along the Kwinana industrial strip, and relationships between CSMC and Local Government Authorities are strong. Regular community forums are also held by CSMC. Hopefully this study highlights areas where other important relationships could be strengthened, where management practices could be improved and where gaps in scientific knowledge are hindering the management of potential groundwater contamination threats to Cockburn Sound. ii Status of Groundwater Quality in the Cockburn Sound Catchment Executive Summary Cockburn Sound Context Cockburn Sound is a marine ecosystem under stress from the pressures of both aquatic and terrestrial human activities. The Western Australian Government has acted to preserve Cockburn Sound for multiple uses, i.e. the Sound will support a balance of urban, industrial and environmental uses. As a societal response to the pressures facing Cockburn Sound, a system of environmental values has been developed for the Cockburn Sound ecosystem under the State Environmental (Cockburn Sound) Policy (SECSP). These values are protected by SECSP and are assessed against quantitative Environmental Quality Criteria (EQC) regularly. Link to Groundwater Quality Seagrass growth and chlorophyll levels are important environmental indicators for Cockburn Sound. Previous scientific studies have drawn a link between these indicators in the seawater of the Sound, and nutrient (mainly nitrogen) levels discharged to the Sound from terrestrial sources. Thus groundwater quality (along with stormwater and industrial effluent quality) is an important factor for the health and sustainability of the Cockburn Sound ecosystem. In turn, this means that groundwater quality must be managed throughout the whole of the Cockburn Sound catchment. Regulatory, Policy and Planning Framework SECSP establishes the basis on which Cockburn Sound is protected. Cockburn Sound Management Council (CSMC) has prepared an Environmental Management Plan for Cockburn Sound and its Catchment (EMP), which implements SECSP. There are no explicit terrestrial environmental values listed in SECSP; all management of terrestrial environmental issues is done under the EMP with the ultimate goal of protecting environmental values within the body of the Sound. The Environmental Protection Act and Regulations are applied across the catchment to license and regulate harmful emissions and discharges. The Contaminated Sites Act is expected to strengthen environmental management when it becomes operative. A Local Planning Policy has been adopted by the three Local Government Authorities (LGAs) and CSMC to ensure a mutual and coordinated approach to the management of Cockburn Sound. At the State level, major new planning initiatives, land use changes and redevelopments must gain environmental approvals from the Environmental Protection Authority. Garden Island is a Commonwealth property managed under the Environmental Protection and Biodiversity Conservation Act. The Australian Defence Force’s Good Neighbour Policy is also applied to environmental management of the island. Major Planning Initiatives A range of significant initiatives are proposed for the catchment, including extensive port facilities and associated land reclamations along the coast, a major new heavy industrial precinct, a proposed large scale marina development and a projected doubling of population in the next few decades. These initiatives will be accompanied by a continuation of the sewage infill program, improved wastewater treatment and recycling, and a decline of intensive horticulture and semi-rural activities in the catchment as large areas of land are rezoned to urban land uses. Managing Groundwater Contamination Industrial, commercial and governmental activities that pose a significant potential risk of contamination can be licensed as prescribed premises under Part V of the Environmental iii Protection Act. There are presently 83 licensed premises within the Cockburn Sound catchment, including companies and organizations across the manufacturing, industrial and service sectors. Many of these premises are located close to the Cockburn Sound shore. Department of Environment monitors these premises for environmental performance and compliance with licence conditions. The Superficial Aquifer The water table across the catchment is located within the Superficial Aquifer, a geologic zone extending typically to approximately 40 m below ground surface (although as much as 100 m deep in places) and containing unconsolidated