A number of river management issues have been apparent for some time within this management zone. These include riverbank erosion, channel instability and channel obstruction. Project Watershed proposes to address these issues in an integrated way, and to clarify roles and responsibilities for the management of existing river works and promoting additional protection. Provision has been made under routine river maintenance for the oversight and basic level of channel management and maintenance.
A greater level of management and protection works is required on some rivers, in particular Tongariro and Tauranga-Taupo. Major additional works are proposed on these rivers to protect local communities. This will complement the existing works, including those recently undertaken on the Tongariro in Turangi by Taupo District Council in 2001. Provision is made under river improvement for this work and should be considered in conjunction with flood protection proposals outlined in section 11.3.3.
The Tongariro River is a constantly changing river system, with Turangi on the entrance to the river delta that continues to actively build. River bed sediments are actively building up and moving through the river channel and have a major influence on the River.
Project Watershed proposals are a combination of both flood protection and river management aimed at preventing, as far as possible, a major river breakout and destruction of property. As a result, the whole of Turangi township benefits from the works. It is reasonable that previously flooded properties which are at greatest risk should pay a higher rate than the rest of Turangi, but with such a volatile river the actual areas of risk are unpredictable.
Gravel management and extraction (local excavations, substantial excavations or commercial extraction) are considered to be an important part of the flood and river control scheme for the Tongariro River. Gravel relocation or extraction would require agreement of landowners and formal consent.
Environment Waikato is intending to develop a gravel management plan in association with stakeholders with specific interests within the local community, in particular the river bed owners, before seeking any consents. The range of environmental effects will need to be fully evaluated before any activity goes ahead. Issues such as sediment discharge effects, alterations to sediment and channel forming regimes, ecological (including fishery) issues, effects on recreational, noise, dust, landscape effects, archaeological sites and cultural issues will all require assessment.
Provision has also been included in Project Watershed costings for lakeshore protection in this zone. These works, previously administered by Taupo District Council, include construction of structures to protect lakeshore assets, such as footpaths and reserves. Existing lakeshore protection assets are valued at $300,000. A further $1.06m of protection assets is scheduled for construction over the next 10 years. Annual maintenance costs are programmed to rise from $10,000 to $44,000 over a similar period.