Don’t swim in Te Awarua-o-Porirua
Summer might be hitting its stride but a recent deluge of rain has prompted Greater Wellington Regional Council to caution swimmers.
Te Awarua-o-Porirua Harbour in Porirua has a warning in place with people being warned not to swim there after the environmental council partnership Land, Air, Water Aotearoa (LAWA) labelled it unsuitable for swimming.
That’s despite it being safe to swim across the harbour at Onepoto, where it is considered it is suitable for swimming despite the fact the regional council’s online water quality tool has graded it C – a moderate risk of illness.
Regional council senior science co-ordinator Penny Fairbrother understood the inconsistencies may cause some confusion, but said data suggested the harbour was unsafe to swim in.
High levels of enterococci were first recorded on December 26, and again on January 3.
The first high readings were due to about 15 millimetres of rain while the second reading may have been due to infrastructure problems, Fairbrother said.
Enterococci, which continues to make the harbour unsuitable for swimming, occurs naturally in people’s stomachs but readings of it usually indicate faecal contamination.
While 35 colony forming units (cfu) per 100 millilitres is considered to be safe, the Wi Neera Dr boat ramp measured 350 cfu/ 100mL on Boxing Day.
The bacteria was similar to the canary in a mine, Fairbrother said.
‘‘[It’s] what we call an indicator bacteria. If those are high, there is likely to be lots of other bacteria and virus-type things present. It’s an indication of contamination.
‘‘No I would not [swim if those were present], no.’’
During summer months, the regional council monitors both sites around Porirua Harbour once a week.
Monitoring at the Wi Neera site began about a year ago, while the council has been taking water samples at Onepoto for more than 10 years.
Contaminants are washed off land and into bodies of water, mainly thanks to rain. However, this can also be a result of infrastructure problems, especially during an overflow, Fairbrother said.
‘‘If there are high bacteria levels and you swim there you could get a stomach bug, and get ill.
‘‘Porirua and some sites around Plimmerton are a bit problematic when it comes to infrastructure.’’
Despite the Boxing Day and January 3 warnings from LAWA and the regional council, the 28th National Scout Regatta went ahead.
Held every three years, about 580 people descended on the harbour to volunteer and take part in sailing, rowing, kayaking, manoverboard scenarios, swimming and ironmans.
Scouts spokesman Daniel Koehler said safety was a priority for all their youth members, and warnings about the harbour were taken into consideration.
‘‘Boxing Day wouldn’t have applied to us because it usually takes about a couple of days for the water quality to return to normal. At the moment, there is a warning for the city-side of the harbour, not where we were swimming.’’