Quarterly Operational Update

FY25 HYDRO
GENERATION
3,410 GWH
MEAN
HYDROLOGY
INCREASES TO
4,140 GWH FROM
FY26
KARĀPIRO
HYDRO REHAB
PROJECT
CONCLUDING
Market summary
Nationalhydrological inflows of 62nd percentile during the quarter contributedto lower spot electricity prices
averaging $216/MWh in Auckland. Forward electricity prices have eased to $179/MWh in Auckland for
financial years 2026 to 2027 as of 30th June 2025.
FY25 hydro generation the 4thlowest from the Waikato scheme since 1980
Total generation for FY25 was 7,906GWh (874GWh,11% lower than PCP). This primarily reflects lower hydro
generation of 3,410GWh (686GWh, 17% lower than PCP) driven by 12th percentile Waikato catchment
inflows and a lower than averageLake Taupō starting level. Lower wind generation of 1,936GWh (125GWh,
6% lower than PCP) from lower wind speeds and lower geothermal generation of 2,559GWh (63GWh, 2%
lower than PCP) from planned outages contributed to the lower FY25 total generation.
For the quarter, a low Lake Taupō leveland dry conditions to start the period contributed to lower hydro
generation of 864GWh (155GWh, 15% lower than PCP). High hydro inflows at the end of the quarterincreased
Waikato catchmentinflows to 79th percentile for the period, providing a healthy hydro storage leading into
FY26.
Increasing mean hydro generation fromDigital River and Karāpiro Rehabilitation
Looking ahead, Mercury’s average annual hydro generation has increased 62GWh to 4,140GWh per annum.
The uplift in the mean hydro expectationsis driven by the Karāpiro Rehabilitation Project and the Digital River,
Mercury’s AI-powered decision platform and digital twin. The Digital River optimises hydro operations by
simulating complex hydrology scenarios for value and has already contributed to record high hydro efficiency
in FY25.
Karāpiroproject concluding with third unit
Mercury is anticipating the completion of the full replacement of the third generating unit at Karāpiro hydro
station in Sep-25, concluding the three-year programme of work at the site. The full replacement of the three
units at Karāpiro increases hydro capacity by 16.5MW, resulting in 32GWh of additional generation assuming
average inflows.

20%
28%
19%
17%
2%
14%
MERCURY
MERIDIAN ENERGY
CONTACT ENERGY
GENESIS ENERGY
MANAWA ENERGY
OTHER
20%
30%
19%
17%
3%
11%
18%
82%
18%
82%

⁰