Energy Link Limited 18/06/2021 Waitaki

Thursday, 17 June 2021 Issue: 1261

A weekly summary relating to hydro storage and inflows. Compiled by Energy Link Ltd. Storage Summary South Island South Island North Island Total Storage Controlled Uncontrolled Total Taupo Current Storage (GWh) 1601 459 2060 71 2130 Storage Change (GWh) 48 120 169 19 188 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) 1925 71 1995 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 187.6 GWh over the last week. South Island controlled storage increased 3.1% to 1601 GWh; South Island uncontrolled storage increased 35.5% to 459 GWh; with Taupo storage increasing 36.2% to 71 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 (2021/22) South Island inflows (2021/22) South Island 2020/21 South Island 2021/22 Waikato 2020/21 Waikato 2021/22 New Zealand Storage (2021/22) New Zealand Storage (2020/21) Average SI Storage (16/17-20/21)

Thursday, 17 June 2021 Manapouri Clutha Waitaki Waikato NZ Storage (GWh) This Week 324 293 1443 71 2130 Last Week 249 242 1400 52 1943 % Change 30.0% 20.9% 3.1% 36.2% 9.7%

Inflow (GWh) This Week 166 117 173 51 507 Last Week 90 60 146 35 331 % Change 84.3% 96.1% 17.9% 46.8% 53.1% Subscribe at www.energylink.co.nz/publications

Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin Energy Link Limited 18/06/2021 Lake Levels and Outflows

Catchment Lake Level Storage Outflow Outflow (m. asl) (GWh) (cumecs) Change Manapouri Manapouri 177.65 106 47 31 Te Anau 202.32 218 Clutha Wakatipu 310.02 58 135 22 Wanaka 277.63 77 225 36 Hawea 342.33 157 67 -46 Waitaki Tekapo 706.98 478 Pukaki 525.93 966 Waikato Taupo 356.02 71

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 26th 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 2nd 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 18/06/2021 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 (2021/22) 2016/17 2017/18 2018/19 2019/20 2020/21 2021/22 Average Maximum Lake Levels

Lake Levels - Lake Taupo storage increased to 12.4% of nominal full at 71 GWh.

Inflows - Inflows increased 46.8% to 51 GWh.

Generation - Average generation decreased 9.7% to 272.6 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 (2021/22) 2016/17 2017/18 2018/19 2019/20 2020/21 2021/22 Average (Last 5 Years) Maximum Lake Levels Minimum Lake Levels Lake Levels - ended the week 56% nominally full with storage increasing to 478 GWh.

Inflows - Inflows into tekapo increased 8.2% to 82 GWh.

Generation - Average Tekapo generation decreased 23.1% to 126 MW.

Hydro Spill - Lake Tekapo did not spill.

Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin Energy Link Limited 18/06/2021 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 (2021/22) 2016/17 2017/18 2018/19 2019/20 2020/21

Lake Levels - Lake Pukaki ended the week 52% nominally full with storage increasing to 966 GWh.

Inflows - Inflows into the Waitaki System increased 28.4% to 90 GWh.

Generation - Average Waikati generation increased 22.9% to 759 MW.

Hydro Spill - Lake Pukaki did not spill.

River Flows - Flows from the Ahuriri River increased to 31.7 cumecs while flows were higher than last week averaging 326.1 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) Inflows 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 (2021/22) 2016/17 2017/18 2018/19 2019/20 2020/21

Total storage for the Clutha System increased by 20.9% to 293 GWh.

Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin Energy Link Limited 18/06/2021 Lake Levels - Total storage for the Clutha System increased by 20.9% to 293 GWh. Lakes Hawea, Wanaka and Wakatipu ended the week 53.3%, 67.3% and 55% nominally full respectively. Inflows - Total Inflows into the Clutha System 96.1% higher at 117 GWh.

Generation - Average generation was 4% higher at 471 MW.

Hydro Spill - The was no estimated spill

River Flows - Total outflows from the lakes and Shotover River increased to 502.9 cumecs. This comprised of 67 cumecs from Lake Hawea, 225 cumecs from Lake Wanaka, 135 cumecs from Lake Wakatipu and 76 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 (2021/22) 2016/17 2017/18 2018/19 2019/20 2020/21

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 (2021/22) 2016/17 2017/18 2018/19 2019/20 2020/21

Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin Energy Link Limited 18/06/2021

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(2021/22) 2016/17 2017/18 2018/19 2019/20 2020/21 2021/22 Average Upper Operating Level Lower Operating Level

Lake Levels - Total storage for the Manapouri System increased by 30% to 324 GWh with Lake Manapouri ending the week 65% nominally full and Lake Te Anau ending the week 79.3% nominally full. Inflows - Total inflows into the Manapouri System increased 84.3% to 166 GWh.

Generation - Average generation was 9.2% lower at 546 MW.

Hydro Spill - Estimated spill at the Mararoa Weir was 47.3 cumecs.

Operating Range - Lake Manapouri is operating in the middle of its 'Main operating range' while Lake Te Anau is operating in the upper end of its 'Main 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 2016/17 2017/18 2018/19 2019/20 2020/21 2021/22 Average Upper Operating Level Lower Operating Level

Ph (03) 479 2475 Consultancy House Email: [email protected] Hydro Watch Dunedin