Horizons Regional Council, via LAWA (Land Air Water Aotearoa), test the river at the footbridge for E. Coli once per week over summer and make the results publicly available, referring to their Traffic Light System.
Green: Suitable for swimming.
Orange: Caution advised – The monitoring result for E. coli was slightly elevated at the time of testing. … young children, elderly or those with compromised health may be at increased risk of illness.
Red: Unsuitable for swimming.
I've now collated the results from 2016 to 2022 and have included them below. Note that start and end dates haven't always been strictly observed, and Covid affected data collection too.
However, we can see that last year had particularly good results, and this year's results have been poor. Over the whole period, our river is generally OK to swim in only 46% of the time. The other 54% of the time the results have been either Orange or Red. We rank a Long-Term grade of Poor.