Environment Waikato is developing new rules to manage the Waikato River during floods.
The Council is responsible for flood management and warning under the Soil Conservation and Rivers Control Act, and power companies Mighty River Power and Genesis also play a significant role in both hydro generation and flood management within the Waikato River catchment.
The existing flood rules are linked to the Tongariro Offset Works Agreement, which expires in March next year, and Environment Waikato is working with other agencies to establish effective arrangements for the river’s future management.
This week’s Operations Committee heard the existing Flood Rules were designed to ensure dam safety and manage flood events in conjunction with the power companies to ensure that there were no additional flood effects from hydro operations. It was essential that the Flood Rules and flood management arrangements continued in the future.
The TOW agreement also recognised the effects of upstream hydro operations on normal flows at Ngaruawahia and provided offset works to deal with them. Future maintenance of these works had been confirmed and were included within Project Watershed.
The Tongariro Power Development Scheme, owned and operated by Genesis, contributes diverted “foreign” water into Lake Taupo and under the agreement, these diversions stop when the Lake reaches or is expected to reach the maximum control level.
The planned agreement is designed to ensure dam safety, have clear agreements on flood management objectives for the whole Waikato River system and establish clear principles and agreements with the power companies. It would also establish new Lake Taupo control targets and new Karapiro outflow control objectives which were consistent with the Lower Waikato Waipa Control Scheme and improved flood management.
Good progress had been made on reaching agreement with the power companies on flood management requirements This included commitment to continuation and improvement of the Flood Management Rules, and establishing clear flood management objectives throughout the Waikato River system from Lake Taupo to Karapiro and Lower Waikato downstream.
Further discussions are to be held with territorial authorities, which were generally supportive of Environment Waikato developing a new flood management regime incorporating existing requirements.