Is it safe to swim in Porirua?
Greater Wellington Regional Council and local councils monitor some of the Wellington region’s most popular beaches and rivers to determine their suitability for recreational activities such as swimming. We monitor eleven coastal sites in the Porirua area. The results from this monitoring are compared to national guidelines and used to calculate an overall grade for each site.
Results from the 2014/15 summer season Recreational water quality in Porirua is quite variable with most sites having an overall grade of ‘C’. The best sites are at Karehana and Onehunga bays. These sites have an overall grade of ‘B’ and the Karehana Bay site met the guideline for safe swimming on all occasions. The worst sites were at the southern ends of Plimmerton Beach and Titahi Bay, and Te Awarua o Porirua Harbour at the Rowing Club. These sites recorded high bacterial counts on one occasion during the 2014/15 summer and have an overall grade of ‘D’.
Very low risk of illness 0% Low risk 18% (2 sites) B
Moderate risk 55% C (6 sites)
Caution 27% (3 sites) D
Unsuitable for swimming 0%
In the Porirua area, 2 sites (18%) are graded ‘B’, 6 sites (55%) are graded ‘C’ and 3 sites (27%) are graded ‘D’.
WAIT TWO DAYS AFTER RAIN before you swim again…
Water quality at Porirua beaches is at its worst after heavy rain. Rain flushes contaminants from urban and rural land into water and we advise people not to swim for two days after heavy rain – even if a site generally has good water quality.
In the Porirua area only six of the 200 samples (3%) taken did not meet the guideline and a third of these were associated with rainfall. Is it safe to swim in Porirua?
Weekly sampling results and overall grades for sites in the Porirua area
2014/15 summer results Overall assessment† Number of Number of samples Most likely Site Name exceedances Risk of Overall exceeding contamination associated contamination grade* the source with rainfall guideline Pukerua Bay 1 1 Urban stormwater Moderate C Karehana Bay at 0 NA Urban stormwater Moderate B# Cluny Road Plimmerton Beach 2 1 Urban stormwater Moderate C at Bath Street Urban stormwater, South Beach 1 0 potential sewage Moderate D at Plimmerton inputs Pauatahanui Inlet 0 NA Urban stormwater Moderate C at Water Ski Club Pauatahanui Inlet 0 NA Urban stormwater Moderate C at Paremata Bridge Urban stormwater, Porirua Harbour at 1 0 potential sewage Moderate D Rowing Club inputs Onehunga Bay Not sampled in 2014/15** Rural land Low B Titahi Bay at 0 NA Urban stormwater Moderate C Bay Drive Titahi Bay at 0 NA Urban stormwater Moderate C Toms Road Urban stormwater, Titahi Bay at South 1 0 potential sewage Moderate D Beach Access Road inputs
† The overall assessment is based on five years of data. * Arrows beside the grade denote whether a grade has increased or decreased from the previous season, ie, # means the grade has improved whereas $ means the grade has declined. ** As water quality at this site is consistently good, weekly sampling is not currently undertaken. The overall grade is based on data collected between 2006 and 2011.
For more information on our Recreational Water Quality Programme check out www.gw.govt.nz/is-it-safe-to-swim For further detail on the 2014/15 results check out our report “Is it safe to swim?” at www.gw.govt.nz/Annual-monitoring-reports For information on recreational water quality across New Zealand check out www.lawa.org.nz Publication number: GW/ESCI-G-15/36 June 2015