The Otago Regional Council (ORC) has resolved to work with Environment Canterbury to take a joint strategic approach to the future management of riparian margins on the Lower Waitaki River.
The chairman of ORC’s engineering and natural hazards committee, Cr David Shepherd, said significant damage to flood control works on the river in the past two years and the resulting impact of this on rating, had raised questions about how best to sustainably manage the river margins.
“The difficulties with managing the riparian margin of what is a large and very active braided river are also exacerbated by damage to riparian margins caused by some landholders on both public and private land,” Cr Shepherd said.
The Lower Waitaki River Liaison Group, comprising representatives of landholders, irrigation companies, Environment Canterbury, Meridian Energy, and ORC, reviews and makes recommendations on annual works programmes and budgets.
The liaison group has agreed that a strategy should be prepared with input from stakeholders and guidance from ORC.
The Lower Waitaki River lies partly in Otago and partly in Canterbury.
Environment Canterbury oversees all of the maintenance works and their planning and the ORC contributes its share of the costs.
Cr Shepherd said the ORC contribution from targeted rates had grown from $70,632 in 2007-2008 to $108,000 in 2010-11.
“These increases are not sustainable, which is why we have decided to act now to manage the area more strategically,” he said.
ORC director of engineering and natural hazards Gavin Palmer said effective riparian management along many parts of the river relied on willows that have colonised naturally on privately-owned land.
Although not established expressly as ‘flood protection and control works’ they achieved the same result and were maintained accordingly by the scheme.
Despite this, some landholders had removed willows on their properties to establish pasture.
“This has a detrimental effect on the river in two ways – it removes vital riparian protection and it establishes higher value land use in vulnerable locations,” Dr Palmer said.
“This in turn places greater reliance on the effective performance of established flood protection and control measures (such as groynes and plantings) and demand for additional river bank protection,” he said.
Environment Canterbury and its predecessors have planted riparian margins along some parts of the river expressly for river control. Despite being “owned” by the scheme, these plantings do not have adequate legal protection from deliberate or accidental damage or removal by landholders, especially in the case of plantings on private land.
Cr Shepherd said that because there were no regulatory controls in place for the Lower Waitaki, it was timely to incorporate provisions into a review of the Otago Flood Protection Management bylaw.
Environment Canterbury is also considering developing a bylaw for the part of the Lower Waitaki that falls within its jurisdiction.
Cr Shepherd said the strategy would review the adequacy of current regional and district plans in relation to the Lower Waitaki River and determine whether additional or different measures are necessary to complement the bylaw(s).
It would cover the river everywhere downstream of Kurow.
Both regional councils would embark on a monitoring programme based on topographic data which would be collected co-operatively. This would ensure duplication of effort did not occur, Cr Shepherd said.