CONTENTS - Part 2

5 WATER 80 7 BIODIVERSITY 112 10 HERITAGE 146

5.1 Current State 80 7.1 Current State 112 10.1 Current state 146 5.2 Increasing water demand 91 7.2 Altered fire regimes 119 10.2 Loss or degradation of heritage sites 153 5.3 Altered water regimes 92 7.3 Loss or degradation of native vegetation 122 5.4 Contamination 94 7.4 Introduced animals, pests and weeds 125 11 BUILT ENVIRONMENT 154 5.5 Salinisation 95 11.1 Current state 154 8 COASTS 128 11.2 Stormwater management 156 8.1 Current State 128 6 LAND 96 11.3 Energy use 156 8.2 Coastal vulnerability 132 6.1 Current state 96 11.4 Waste generation and disposal 157 8.3 Loss or degradation of coastal habitat 133 6.2 Declining land capability 103 6.3 Acid sulphate soils 109 12 MONITORING & REPORTING FRAMEWORK 158 6.4 Land contamination 111 9 MARINE ENVIRONMENT 136 12.1 Indicators and measuring change 158 9.1 Current State 136 9.2 Degradation of the marine environment 141 9.3 Introduced pests 144 13 REFERENCES 164 9.4 Over-fishing 145 Appendix A – BIodiversity listings 167

Pilbara state of the environment report 2013 5. WATER

5.1 Current State of the central and discharge over the Most runoff occurs during the period January to systems. The flood potential of a system is coastal plains into the Indian Ocean. The east March, largely as a result of cyclonic activities, not directly related to cyclone intensity but is As noted in section 3.3, the Pilbara Pilbara is drained predominantly by the Mackay with typically less runoff during December and associated with its track, speed, areal extent region contains some of ’s Basin and the Sandy Desert Basin which contains April (WAPC, 2009). Mean annual runoff rates and saturation of catchments from prior rainfall. consistently hottest places with highly extensive areas of salt lake chains. The Pilbara from the major rivers in the Pilbara region Indeed rainfall totals in excess of 100 mm are irregular rainfall, where the average Surface Water Area, which covers the western typically represent 2.5% to over 10% of the common with tropical lows that move over land. half of the Pilbara, is proclaimed under the annual rainfall. In February 1997 a slow moving low moved yearly evaporation (approximately Rights in Water and Irrigation Act 1914 for the over the west Kimberley, Pilbara and Open cut mining in the Pilbara results in the 3,000mm) exceeds average yearly purposes of regulating the taking of water from causing rainfall in excess of 400 mm in parts creation of massive voids, such as the BHP rainfall. This climate, which can watercourses and wetlands. and one of the highest ever floods along the Billiton-owned pit at Mount Whaleback near Ashburton River. Cyclone Joan in December 1975 result in severe droughts and major Stream flows in the Pilbara region are mostly a Newman. Acid rock drainage was not originally caused over 400 mm of rain near its track, the floods simultaneously occurring direct response to rainfall, and as such they are considered a serious concern in the Pilbara due highest fall being 591 mm at Marandoo (BoM highly seasonal and variable. With the exception to the low rainfall and high evaporation rates over the region, supports a unique 2012a). and rich landscape of biodiversity of some small but important, spring-fed sections, experienced in the region. However, acidic all waterways in the region are ephemeral, in runoff was detected from a storage area at Flooding is enhanced when multiple tropical and water resources, which include that surface flow ceases for at least part of each Mount Whaleback in 1995, following the heavy lows occur within a few weeks of each other. many waterways, wetlands and year. The major rivers of the region (in order of rains resulting from Cyclone Bobby (Johnson During January and February 1961 rainfall totals groundwater resources. highest to lowest mean annual flow) are the De and Wright, 2001).