Waikato Hydro Scheme The Waikato River flows from

Waikato Hydro Scheme • The Waikato River flows from an elevation of 357 m at the Taupo control gates to 22 m at the base of Karapiro power station, a difference of 335 m over a distance of 186 km. • The Taupo gates provide some control over the discharge from Lake Taupo. • The damming of the Waikato River forms eight long, narrow reservoirs in each of the flooded river valleys. The upper part of the river between Lake Taupo and Lake Ohakuri remains largely riverine and includes Huka Falls. • For all power stations between Ohakuri and Karapiro the tailrace of the upstream dam is the headwaters of the downstream reservoir there are no riverine sections left in that portion of the river, as shown in Figure above.

Waikato Hydro Scheme Long-term assets commissioned between 1929 and 1970

Waikato Hydro Scheme • 100% own and operate nine power stations along the Waikato River • Flexible – output can be increased or decreased quickly and efficiently • 2 x Kaplan Stations (Waipapa & Karapiro), 7 x Franis Stations, Taupo Control gates

Waikato Hydro Scheme • Lake Taupo storage -integral part of the scheme -representing 14% of national hydro storage. The available storage within Lake Taupo water is cycled on average 5. 8 times per year. • The Waikato Hydro Scheme has eight dams and nine power stations (with a total of thirtynine generating units) with a total rated dependable capacity of approximately 1048 megawatts. On average 4000 GWh of electricity generated each year. • Resource consents granted by Waikato Regional Council authorise the take, dam, diversion of water to April 2041. Extensive conditions regulate the maximum and minimum operating levels for Lake Taupo and each reservoir along with minimum flows at Lake Taupo, Aratiatia dam and Karapiro dam & provides reliability for downstream users • Waikato Hydro Scheme relies on the diversions associated with the Tongariro Power Scheme operated by Genesis Energy Ltd, which adds another 654 km 2 to the overall Waikato catchment and increases the mean Waikato River flow by approximately 20% at the Taupo control gates.

Hydro re-investment programme • Decade long programme of work that represents that largest-ever lifecycle and maintenance investment in Mighty River Power’s hydro assets. • A focus on ensuring high levels of efficiency, improved availability and reliability. • Respecting heritage and original construction, while applying state of the art technology to achieve gains in performance. > Arapuni Generators $20 M, Ohakuri Runner Project $30 M, Arapuni Diversion Tunnel $30 M > Planned: Whakamaru rehabilitation, Aratiatia rehabilitation, Karapiro & Atiamuri Class 4 s Transformers, governors etc.

Aquatic Weed Aquatic weed management Extent of the problem • Circa $1 m direct annual control cost to Mighty River Power • Potential for significant business interruption costs • Improved monitoring, planning and reliance on “toolbox” of methods • Control Methods • Diquat - 100 -150 ha treated annually, very effective tool - Support WRC permitted activity status • Harvester - Dates back to 1980’s, 200 m 3/day • Shredder - Consented in 2008, 100 m 3/hour • Booms, screen cleaners, intake screens, spilling water • Responsibility • LINZ agency responsible for weed control on bed of Waikato Lakes

Involvement in our communities • 15 -year relationship with New Zealand Rowing • Supporting Starship Children’s Hospital, together with our customers, for more than a decade. Mercury Energy and our Star Supporters Club raised a record $1 million last year • Involved in Taupo Ironman for the past six years - enable 2, 000 strong volunteer crew for event support • Partnerships with Waikato River Iwi • • Waikato Catchment Ecological Enhancement Trust (WCEET) Established with funding from Mighty River Power as part of hydro consenting process $3. 2 million invested in 168 projects (a further $1. 34 million committed) • • Waikato River Trails - Cornerstone sponsor, MRP staff co-opted Trustees • Long-term sponsors Taupo Coastguard and Sailing

River Environment Today Lakes now a valued part of the environment