Currently river management activities in the zone are limited to riverbank maintenance in localised areas and some maintenance of the Waipa River channel.
Provision has been made in the proposed project estimates for routine river maintenance over 370 km of stream lengths in the management zone. Proposed activities include the provision of information and advice, channel maintenance, vegetative management and supervision within the main channels of priority waterways. It is proposed that much of the day-to-day work be completed by landowners.
At present the relevant district councils undertake limited river maintenance work in the main channels within drainage districts still operative in the zone. It is proposed that these activities be undertaken by Environment Waikato under routine river maintenance.
River improvement works have also been suggested for the zone. These include training and stabilising the Waipa River channel to allow gravel in the system to be transported through. The cost estimate for river improvement is $1.53m. Of this, $835,000 is involved in works upstream of the Toa bridge and is accounted for in the separate Tunawaea landslide and river works funding policy.
A further $110,000 is estimated to be required for investigating the flooding that occurs within the Mangapu, Mangaokewa and Mangawhero river systems. This has been provided for.
The (former) Upper Waipa Liaison Subcommittee expressed concern that a large sum of money could be spent on an investigation, and at the end of the investigation no works may proceed as the project may well be uneconomic. The Subcommittee has recommended that the proposed investigation into flooding in these catchments be reconsidered. It was suggested that the investigation be staged so that at the end of each stage the project could be reviewed, and if appropriate, could be terminated.
Accordingly these investigations have been phased over six years starting from 2004. The work will be structured in such a way that if ‘desk investigation’, (including a review of existing information) of each of stream does not reveal sufficient benefit, the subsequent field investigations will not proceed. No allowance has been made in Project Watershed estimates for any capital works that may be initiated as a consequence of these investigations. A separate funding policy, that may include a differential rate, would be developed if it were decided to proceed with works.
Flood protection currently comprises stop banks to protect the township of Otorohanga. These are currently maintained and funded by the Otorohanga District Council. This is largely funded by lease rentals.
The Mangawhero Stream channel that drains the Kawa Drainage District has been identified as requiring substantial improvement to relieve the flooding that occurs within the Kawa basin. Subcommittee members have requested that the improvement works be included in the proposed programme.
The existing Kawa drainage area stopbank scheme has been provided for in Project Watershed estimates as a flood control work. Capital work, estimated at $89,000 spread over two years, is required to bring the scheme up to the agreed standard, and the annualised cost of maintaining the scheme is estimated at $15,000. This cost includes inspections, maintenance and refurbishment costs associated with the stopbanks and floodgates.