New Lake Level Guidelines to Boost Hydro Power and Energy Security in NZ

In a significant move to bolster New Zealand’s renewable energy output and improve resilience in the national grid, the Guardians of Lakes Manapōuri and Te Anau and Meridian Energy have jointly agreed to updated Operating Guidelines for lake level management. The revised guidelines, recently formalised by Energy Minister Simon Watts, are expected to unlock an additional 45 gigawatt-hours (GWh) of hydroelectric energy per year from the Manapōuri Power Scheme—enough to power around 6,000 homes annually.

The change represents a key development in the Government’s drive to improve the reliability and affordability of energy supply in New Zealand, particularly in response to energy supply constraints and price surges experienced during Winter 2023.

A Strategic Response to Last Winter’s Energy Shortage

“Last winter, New Zealand faced an energy shortage that led to significant price increases for consumers, in part due to low hydro lake levels,” said Minister Watts. “This Government will not accept a repeat of last winter and is working at pace to ensure we have a reliable and affordable energy supply.”

Hydroelectricity is a cornerstone of New Zealand’s energy infrastructure, contributing over 50% of the country’s electricity generation. However, low water levels in major storage lakes—particularly during dry seasons—can significantly reduce output and force reliance on more expensive and carbon-intensive generation sources such as gas or coal.

By revising the lake drawdown protocols, Meridian Energy will now have more operational flexibility to continue generating electricity even when lake levels are low, thus providing a crucial buffer during periods of high demand and limited supply.

Balancing Energy Needs and Environmental Stewardship

Lake Manapōuri and Lake Te Anau are not only energy assets but are also deeply valued environmental and cultural treasures. The lakes reside within the Fiordland National Park, part of the Te Wāhipounamu World Heritage Area, and are subject to strict environmental oversight.

In recognition of these sensitivities, the new guidelines were developed collaboratively by the Guardians of the Lakes—a statutory body responsible for advising on environmental, ecological, and social effects—and Meridian Energy, the operator of the Manapōuri Power Station.

“The agreement reached today allows for more flexible drawdown rates once the lakes reach lower operating levels, enabling Meridian to continue generating when lake levels are low,” said Minister Watts. “The changes balance the needs of our country’s electricity system with the environmental impact on the lakes and their surrounding areas.”

This approach ensures that ecological stability, shoreline health, recreational access, and cultural values remain protected while supporting the energy system.

Legal and Policy Backing for the Changes

The new operational protocols were officially enacted through legislative amendment and have been published in the New Zealand Gazette, ensuring transparency and legal clarity.

Minister Watts praised the collaborative spirit of the process, stating: “I acknowledge the expertise of the Guardians and Meridian for working together to recommend a path forward that better protects the existing patterns, ecological stability, and recreational values of the lakes, while optimising hydro generation.”

This decision reflects a broader Government push to make New Zealand’s energy system more climate-resilient, sustainable, and affordable, while reducing dependency on fossil fuels.

Looking Ahead: Energy Resilience and Climate Goals

The additional 45 GWh of hydroelectric energy output, though modest in scale, is strategically valuable in shaving peak demand, reducing spot market volatility, and contributing to the country’s 2030 and 2050 emissions reduction goals.

The new guidelines serve as a model for how environmental conservation and energy production can be harmonized through transparent dialogue, scientific input, and community engagement.

As the energy sector braces for greater climate uncertainty and rising demand from electrification of transport and industry, initiatives like this will play an essential role in ensuring New Zealand’s transition to a clean, secure, and inclusive energy future.