The southern approach to the State highway 6 Wanganui River bridge. Photo: Greymouth Star / Brendon McMahon
Work to bolster stopbanks on the south bank of the Wanganui River at Hari Hari "needs doing urgently".
In the past six weeks the river has turned towards old rockwork about 1.5km below the State Highway 6 bridge, threatening farmland and risking it cutting a new course through the Wanganui Flat below the township of Hari Hari.
"There's emergency works needs doing urgently down there. It's a matter of the rating district sorting out what they want to do," West Coast Regional Council chairman Peter Haddock said on Monday.
"I believe it's significant. It needs doing because the river has turned towards the south bank. I believe some of that on the south bank isn't armoured so it is vulnerable to erosion - some of that work would be around trying to divert the river away."
Wanganui Rating District Committee spokesman Jon Sullivan said a riverbank meeting on Friday with council staff and the affected parties had assessed the situation.
"I'm trying to get the thing going. The trouble is there is no bloody money... they're going ahead and hopefully they'll get some money from somewhere."
What had been agreed was "a band-aid job" in the meantime.
This was if something was not done to stop further incursion by the river then a proper fix up would quickly escalate into the hundreds of thousands of dollars.
Sullivan said big pieces of 10 to 12-tonne rock sitting at the river's edge, and historically the line of defence for the gravel stopbank further away from the water's edge, were now "just getting washed away".
Conditions in the river on Monday were moderate, although it was hard to know what rain was falling inland.
"We're anticipating a bit of rain," he said.
Regional council management told the April council meeting that investigation to install rainfall monitor warning equipment on the Wanganui River was well advanced.
Sullivan said a "proper job" on the bank would be cheaper in the long run - over three to five years - but it had been deemed too expensive last Friday.
In the meantime, the current stopbank would hold pending a diversion of the river away from the weak southern bank protection.
"It will be alright as long as it doesn't p**s down in the next couple of days."
However, Sullivan - who has farmed immediately above the weakened floodbank for over four decades - said it was another case of less than active river management at the top end of the flood scheme, nearer State highway 6.
"There has been no work up here for 40 to 50 years - it's been all down the bottom."
Meanwhile, the recent budget has dashed hopes the regional council might benefit from new funding for the Wanganui River scheme this coming year through a new climate resilience fund.
The council applied as part of a joint application sponsored by the wider regional council river engineers sector group.
Haddock said some of the work needed on the Wanganui south bank would have to be new capital work.
He had suggested council staff hold an urgent meeting of the rating district committee to weigh the cost to the rating district, alongside individual capital costs to affected ratepayers, at the same time as river engineering staff assessed the process for the immediate emergency work.
Local Democracy Reporting is Public Interest Journalism funded through NZ On Air.
