The source of dangerously high pollution levels in the Waikato River has been narrowed to discharges by one of five companies.
Environment Waikato has been testing the river between Cambridge and Hamilton since bacteria levels were found to be more than seven times the safe limit for swimming.
Environment Waikato spokesman Tony
Petch said yesterday that new testing had narrowed the focus to a stretch of only several hundred metres 6km downstream of Cambridge.
He also revealed that the pollution had been pouring into the river for months, and probably for up to a year.
He would not name the companies on the shortlist.
The pollution is believed to be from a single source because of the large increase in bacterial counts over such a short stretch of the river.
The latest results, from testing last Wednesday, have shown faecal bacteria counts even higher than those taken three weeks ago.
On April 13 Waikato's medical officer of health, Dell Hood, warned that people should not swim in, row on or walk too close to the river.
Counts of e-coli, an indicator of the presence of animal or human faeces, downstream of Cambridge on April 7 were as high as 3000. Under national guidelines the acceptable limit for swimming from a single sample is 410.
Mr Petch said yesterday that counts were now even higher than those that had prompted Ms Hood's warning.
The regional council said the pollution downstream of Cambridge had shown up in test results at the Narrows - halfway between Cambridge and Hamilton - for the past year.
- NZPA
nzherald.co.nz/environment
