An investigation is underway into an environmental breach after materials from a power pole installation were dumped in a Southland waterway.

The matter relates to a controversial PowerNet project on the outskirts of Invercargill where 21 metre-high power poles are being installed along a 19.5 kilometre route from Awarua to a city substation.

A spokesperson for PowerNet, the company responsible for the installation, said some items were temporarily placed in a culvert for safety reasons, but these would not have caused adverse effects on the environment.

Motu Rimu Rd resident Jacques Nel doesn’t have a problem with the lines going in, but said he was upset to find materials left in a waterway near his property, which is home to a range of fish.

Large metal structures appeared last week, and were confirmed by the regional council to have caused a breach.

Nel said the creek was tidal, and home to a range of wildlife including eels, trout, herons and spoonbill.

Motu Rimu Rd resident Jacques Nel says the stream next to the road is tidal, and home to an array of different fish. PowerNet is installing 21-metre poles along the road as part of a project which will run from Awarua through to Invercargill. Photo: Matthew Rosenberg/LDR

“At the end of the day, it’s heartbreaking to see something you’ve looked after that’s getting destroyed by muck and (what) looks like cement on top of the water.”

He said he tried to avoid things like pesticides on his farm and believed the creek’s ecosystem was relatively healthy.

“People should think before they do things, because there’s someone that’s responsible for this.”

The structures were removed earlier this week, with PowerNet saying it had not left any materials in or near a stream that could adversely affect the environment.

“A metal pole liner and mesh frame were temporarily placed in the culvert alongside Motu Rimu Road to keep them off the road for safety purposes,” a spokesperson said.

“We will take any action needed to make sure natural ecosystems are not damaged or negatively impacted by our work wherever necessary. In this instance, no action is required.”

In relation to Nel’s concern cement had been dumped, PowerNet said some of the material they had dug up was a sandy grey clay which had that appearance.

Environment Southland senior scientist Katie Blakemore said most of New Zealand’s native fish were migratory and it was common for tidal streams to have a high level of diversity.

LDR is local body journalism co-funded by RNZ and NZ On Air