Residents living along Rocks Rd., Wakefield Quay & Tahunanui Drive (by the beach) were surprised when they spotted a stream running fluorescent green in the ocean.
One resident, said the stream on the beach end was "bright green" on Wednesday morning.
"It runs down into a big grate, which is about 4 square metres, where it runs under the road and it was green down there too, so there was obviously a lot of whatever going on.
The stream above the catch pit was clear so it looked like something had been poured down into the catch pit on the road, she said.
NCC’s technical services manager said the cause of the discolouration was an organic fluorescein dye used by contractors to identify where underground infrastructure is located. This highlights faults/breaks in pipe lines too.