Energy Link Limited 1/10/2020 Waitaki Thursday, 01 October 2020 Issue: 1224 A weekly summary relating to New Zealand hydro storage and inflows. Compiled by Energy Link Ltd. Storage Summary South Island South Island South Island North Island Total Storage Controlled Uncontrolled Total Taupo Current Storage (GWh) 984 756 1740 255 1994 Storage Change (GWh) 132 96 228 102 330 Note: SI Controlled; Tekapo, Pukaki and Hawea: SI Uncontrolled; Manapouri, Te Anau, Wanaka, Wakatipu Transpower Security of Supply South Island North Island New Zealand Current Storage (GWh) 1567 255 1822 Note: These figures are provided to align with Transpower's Security of Supply information. However due to variances in generation efficiencies and timing, storage may not exactly match Transpower's figures. New Zealand Summary Total storage increased 330.2 GWh over the last week. South Island controlled storage increased 15.4% to 984 GWh; South Island uncontrolled storage increased 14.6% to 756 GWh; with Taupo storage increasing 67.3% to 255 GWh. New Zealand Storage and Inflow Summary 5000 2000 4500 1750 4000 1500 3500 1250 3000 2500 1000 Clutha 2000 750 Storage (GWh) Storage 1500 (GWh) Inflows 500 1000 250 500 0 0 May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Month Taupo Inflows (2020/21) South Island inflows (2020/21) South Island 2019/20 South Island 2020/21 Waikato 2019/20 Waikato 2020/21 New Zealand Storage (2020/21) New Zealand Storage (2019/20) Average SI Storage (15/16-19/20) Thursday, 01 October 2020 Manapouri Clutha Waitaki Waikato NZ Storage (GWh) This Week 583 244 913 255 1994 Last Week 512 197 803 152 1664 % Change 13.9% 23.7% 13.7% 67.3% 19.8% Inflow (GWh) This Week 281 142 193 129 745 Last Week 234 123 172 50 579 % Change 20.2% 15.6% 12.1% 158.3% 28.8% Subscribe at www.energylink.co.nz/publications Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin Energy Link Limited 1/10/2020 Lake Levels and Outflows Catchment Lake Level Storage Outflow Outflow (m. asl) (GWh) (cumecs) Change Manapouri Manapouri 179.03 188 346 250 Te Anau 203.50 395 Clutha Wakatipu 310.29 79 277 59 Wanaka 277.97 94 323 63 Hawea 340.00 71 11 -1 Waitaki Tekapo 705.32 309 Pukaki 523.11 604 Waikato Taupo 356.47 255 Inflow Summary The two charts below represent where current inflows are in relation to historic inflow patterns. The percentile values have been calculated using all inflows since 1931. South Island Inflows - The past four weeks of S. I. inflows rank as the 8th wettest on record. South Island Inflow Percentile Data 4 week running average 1200 99%ile 1000 95%ile 75%ile 800 Median 600 25%ile GWh 400 5%ile 1%ile 200 4week 0 inflow Month North Island Inflows - The past four weeks of N. I. inflows rank as the 34th driest on record. North Island Inflow Percentile Data 4 week running average 140 99%ile 120 95%ile 100 75%ile 80 Median 25%ile GWh 60 5%ile 40 1%ile 20 4week inflow 0 Month Waikato System Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin Energy Link Limited 1/10/2020 Waikato System Lake Taupo Levels and Inflows 357.50 250 Maximum Lake level 357.00 200 356.50 150 356.00 100 Minimum Lake level Lake Lake level (m) 355.50 50 (GWh)Inflows 355.00 0 May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Month Taupo Inflows (2020/21) 2015/16 2016/17 2017/18 2018/19 2019/20 2020/21 Average Maximum Lake Levels Lake Levels - Lake Taupo storage increased to 44.6% of nominal full at 255 GWh. Inflows - Inflows increased 158.3% to 129 GWh. Generation - Average generation decreased 6.2% to 273.4 MW. Tekapo Lake Tekapo Levels and Inflows 712 220 200 Maximum Lake level 710 180 160 708 140 120 706 100 80 704 60 Inflows (GWh)Inflows Lake Lake Level (m) 702 40 Minimum Lake level 20 700 0 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Month Tekapo Inflows (2020/21) 2015/16 2016/17 2017/18 2018/19 2019/20 2020/21 Average (Last 5 Years) Maximum Lake Levels Minimum Lake Levels Lake Levels - Lake Tekapo ended the week 43% nominally full with storage increasing to 309 GWh. Inflows - Inflows into tekapo increased 35.6% to 79 GWh. Generation - Average Tekapo generation increased 30% to 88 MW. Hydro Spill - Lake Tekapo did not spill. Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin Energy Link Limited 1/10/2020 Waitaki System Lake Pukaki Levels and Pukaki/Ohau Inflows 535 240 533 220 Maximum Lake level 200 531 180 529 160 527 140 525 120 523 100 80 521 Inflows(GWh) Lake Lake Level (m) 60 519 40 Minimum Lake level 517 20 515 0 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Month Pukaki/Ohau Inflows (2020/21) 2015/16 2016/17 2017/18 2018/19 2019/20 Lake Levels - Lake Pukaki ended the week 34% nominally full with storage increasing to 604 GWh. Inflows - Inflows into the Waitaki System increased 0.2% to 115 GWh. Generation - Average Waikati generation increased 8.2% to 547.2 MW. Hydro Spill - Lake Pukaki did not spill. River Flows - Flows from the Ahuriri River increased to 63.3 cumecs while Waitaki River flows were higher than last week averaging 252.1 cumecs. Clutha System Lake Hawea Levels and Inflows 347 Maximum Lake level 34 32 345 30 28 26 343 24 22 341 20 18 16 339 14 12 337 Normal Minimum 10 Inflows(GWh) Lake Level Lake Level (m) 8 Emergency Minimum Lake 6 335 4 2 333 0 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Month Hawea Inflows (2020/21) 2015/16 2016/17 2017/18 2018/19 2019/20 Total storage for the Clutha System increased by 23.7% to 244 GWh. Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin Energy Link Limited 1/10/2020 Lake Levels - Total storage for the Clutha System increased by 23.7% to 244 GWh. Lakes Hawea, Wanaka and Wakatipu ended the week 24.1%, 82.1% and 74.3% nominally full respectively. Inflows - Total Inflows into the Clutha System 15.6% higher at 142 GWh. Generation - Average generation was 4.1% higher at 583 MW. Hydro Spill - Estimate Spill is 84.6 cumecs. River Flows - Total outflows from the lakes and Shotover River increased to 717.8 cumecs. This comprised of 11 cumecs from Lake Hawea, 323 cumecs from Lake Wanaka, 277 cumecs from Lake Wakatipu and 107 cumecs from the Shotover River. Lake Wanaka Levels and Inflows 281 100 90 280 80 70 279 60 278 50 40 277 30 Inflows (GWh)Inflows Lake Lake Level (m) 20 276 10 275 0 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Month Wanaka Inflows (2020/21) 2015/16 2016/17 2017/18 2018/19 2019/20 Lake Wakatipu Levels and Inflows 100 311.8 90 311.4 80 70 311 60 310.6 50 310.2 40 30 Lake Lake Level (m) 309.8 Inflows(GWh) 20 309.4 10 309 0 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Month Wakatipu Inflows (2020/21) 2015/16 2016/17 2017/18 2018/19 2019/20 Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin Energy Link Limited 1/10/2020 Manapouri System Lake Manapouri Levels and Manapouri/Te Anau Inflows 182 400 360 181 320 180 280 Upper Operating Level 179 240 200 178 160 177 120 Inflows(GWh) Lake Lake Level (m) Lower Operating Level 80 176 40 175 0 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Month Manapouri/Te Anau Inflows(2020/21) 2015/16 2016/17 2017/18 2018/19 2019/20 2020/21 Average Upper Operating Level Lower Operating Level Lake Levels - Total storage for the Manapouri System increased by 13.9% to 583 GWh with Lake Manapouri ending the week 115.9% nominally full and Lake Te Anau ending the week 143.5% nominally full. Inflows - Total inflows into the Manapouri System increased 20.2% to 281 GWh. Generation - Average generation was 3.2% lower at 738 MW. Hydro Spill - Estimated spill at the Mararoa Weir was 346 cumecs. Operating Range - Lakes Manapouri and Te Anau are operating in the middle of their respective 'High operating range'. Lake Te Anau Levels 205 204 Upper Operating Level 203 202 Lake Lake Level (m) Lower Operating Level 201 200 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Month 2015/16 2016/17 2017/18 2018/19 2019/20 2020/21 Average Upper Operating Level Lower Operating Level Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin.