The location of the dump is just 50m upstream of a water supply intake for the town of Levin. It's known as 'the snake' because it's a redundant flood-water overflow filter which looks like a large zig-zagging drain.
After discovering the dump, the man took his concern to Horowhenua District Council (HDC), which had given permission to Downers to fill the drain with clean waste.
Manager of Infrastructure Services at HDC, Gallo Saidy considered the complaint.
"I think it was a genuine mistake from the contractor because I've investigated... and the conclusion is the area was used for fill but it was not clear to the driver it was for clean fill," Saidy said.
The HDC said only a couple of truck loads were dumped and they've been removed or buried on site. Something the tramper says is not good enough.
But the council maintains there's no threat to the town's water supply anyway.
"From the river to this point [the dump site] is around 30m and to the [water] intake is about 50m so it's far away from the river.
The pipe where we get the water from is 5m below the ground... so there's no chance there could have been leaching.
"No chance at all for that to happen given the number of loads that were here. Even if the loads were 100 trucks, the chance of contaminating the water supply is very slim," Saidy said.
Horizons Regional Council manages the region's waterways and said it was looking into what consents were issued.
Downers issued a statement saying it was not the only one dumping fill at the site, and the two loads of waste it dumped have been removed.
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