THE BASIN PLAN Water quality technical report for the Border Rivers surface water resource plan area (SW16) NSW Department of Planning, Industry and Environment | dpie.nsw.gov.au Published by NSW Department of Planning, Industry and Environment dpie.nsw.gov.au Title: Water quality technical report for the Border Rivers surface water resource plan area (SW16) First published: February 2020 Department reference number: INT18/12429 Acknowledgments The soils maps in this report contain data sourced from the NSW Office of Environment and Heritage. © State of New South Wales through Department of Planning, Industry and Environment [2020]. You may copy, distribute, display, download and otherwise freely deal with this publication for any purpose, provided that you attribute the Department of Planning, Industry and Environment as the owner. However, you must obtain permission if you wish to charge others for access to the publication (other than at cost); include the publication in advertising or a product for sale; modify the publication; or republish the publication on a website. You may freely link to the publication on a departmental website. Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (October 2018) and may not be accurate, current or complete. The State of New South Wales (including the NSW Department of Planning, Industry and Environment), the author and the publisher take no responsibility, and will accept no liability, for the accuracy, currency, reliability or correctness of any information included in the document (including material provided by third parties). Readers should make their own inquiries and rely on their own advice when making decisions related to material contained in this publication. Water quality technical report for the Border Rivers surface w ater resource plan area (SW16) Summary Good quality water protects public health, supports economic production and maintains a healthy river ecosystem. Water quality is mostly determined by land use, geology, climate, riparian vegetation and stream flow, and reflects the interactions of natural and man-made practices that occur in a drainage area and the riparian zone. Degradation of water quality can put stress on a range of aquatic organisms, impinge on Aboriginal cultural and spiritual uses of water, increase the cost of drinking water treatment, contribute to public health risks and decreases the suitability of water for irrigation and agriculture. Alteration of the Australian landscape since European settlement has resulted in marked changes in catchment conditions. Runoff from cropping areas, erosion of soil and nutrients from stream banks, and discharge from saline areas have led to increased turbidity, salinity, sedimentation, nutrient loads and chemical residues. These in turn can degrade aquatic ecosystem health. The regulation of rivers through the construction of large storages and weirs lead to changes to flow regimes, thermal pollution, harmful algal blooms and disruption of longitudinal connectivity of river processes. Water quality condition in the Border Rivers water resource planning area (WRPA) varies from poor to excellent. Water quality issues occurring within the catchment are the result of a combination of factors. These include alteration to natural flow regimes, in particular disruption by Pindari Dam, changes to catchment conditions and land use change. Table 1 summarises the major water quality issues in the Border Rivers WRPA. Table 1: Summary of major issues and causes of water quality degradation Issue Location Potential causes Harmful algal uplands Stratification and warm water temperatures in Pindari Dam, Boggabilla Weir and Lake blooms Inverell. Low flows in lower Macintyre River. Nutrient inputs. Dissolved uplands, Reduced flow and increased low flow and cease to flow periods disrupting dissolved oxygen and pH midlands, oxygen dynamics and increasing eutrophication. outside of lowlands normal ranges Increased uplands, Stream bank and riparian condition, grazing and cropping practices, carp and feral nutrients and midlands, species. In the lowlands, increased sediment and nutrient input associated with turbidity lowlands erosion. Toxicants and uplands, Pesticide use in cropping areas, toxicants from historical mining activities. pesticides midlands, lowlands Disruption to midlands, Reduced freshes and high flows, disruption of longitudinal connectivity by Pindari organic carbon lowlands Dam. cycling Thermal midlands Cold water released from Pindari Dam in summer. Warm water releases in winter. pollution NSW Department of Planning, Industry and Environment | INT18/12429 | i Water quality technical report for the Border Rivers surface w ater resource plan area (SW16) Contents Summary ...................................................................................................................................................... i Contents ...................................................................................................................................................... ii List of tables ................................................................................................................................................ iv List of figures............................................................................................................................................... iv 1. Introduction ...........................................................................................................................................1 1.1. Purpose..........................................................................................................................................1 1.2. Context...........................................................................................................................................2 1.3. Catchment description ....................................................................................................................3 1.4. Water quality targets .......................................................................................................................3 1.4.1. Assessment using Basin Plan water quality targets ...................................................................4 1.4.2. Water quality targets for water-dependent ecosystems ..............................................................5 1.4.3. Water quality targets for raw water for treatment for human consumption ...................................6 1.4.4. Water quality targets for irrigation water ....................................................................................6 1.4.5. Water quality targets for recreational water ...............................................................................6 1.4.6. Salinity targets for long-term salinity planning and management.................................................7 2. Water quality parameters .......................................................................................................................8 2.1. Turbidity and suspended sediment ..................................................................................................8 2.2. Nutrients .........................................................................................................................................8 2.3. Dissolved oxygen ............................................................................................................................9 2.4. pH ................................................................................................................................................ 10 2.5. Water temperature and thermal pollution ....................................................................................... 10 2.6. Salinity ......................................................................................................................................... 11 2.7. Harmful algal blooms .................................................................................................................... 12 2.8. Toxicants ...................................................................................................................................... 13 2.9. Pathogens .................................................................................................................................... 13 3. Water access rules and flow management in the Border Rivers WRPA .................................................. 14 4. Methods .............................................................................................................................................. 16 4.1. Site selection and monitoring ......................................................................................................... 16 4.2. Water quality index (WaQI) ........................................................................................................... 18 4.3. Catchment stressor identification ................................................................................................... 19 4.3.1. Conceptual mapping .............................................................................................................. 19 4.3.2. Literature review .................................................................................................................... 19 4.3.3. Summary statistics ................................................................................................................