2014/15 beach and river water quality report

Over the long hot summer Otaki River, Breaker and Princess bays and Waingawa, Waiohine and Tauherenikau rivers were the top spots for swimming.

The preliminary analysis of 2014/15 beach and river water quality data collected by Greater Wellington Regional Council and local councils have been released and show that the best swimming spots in the region were at sites on the Otaki River (Kāpiti Coast), Breaker and Princess bays (Wellington City) as well as Waingawa, Waiohine and Tauherenikau rivers (Wairarapa).

These swimming spots had bacteria counts that met the guideline for safe swimming on all sampling occasions and had an overall grade of 'A' (see below key to grades). Also, none of these sites were affected by toxic algae blooms.

Parts of Plimmerton Beach, Te Awarua o Porirua Harbour and Titahi Bay in Porirua, Island and Owhiro bays in Wellington City, Rona Bay, the Hutt and Wainuiomata rivers in the Hutt, Ruamāhanga River and Riversdale Lagoon in the Wairarapa all had bacteria counts that didn't meet the guideline for safe swimming on at least one occasion and had an overall grade of 'D'.

Also, both the Hutt and Ruamāhanga rivers were affected by toxic algae blooms over the summer but all toxic algae warnings have now been lifted.

As expected the best sites tend to be those in forested areas or those with relatively low intensity land use while the worst sites tend to be in urban areas where discharges from stormwater and sewerage infrastructure can occur or in rural areas affected by treated sewage discharges or rural runoff.

The worst time to swim is after heavy rainfall when high bacteria counts tend to occur due to contaminated runoff being washed into rivers and the coast. Contamination levels tend to dissipate 48 hours after rain has stopped.

The online recreational water quality survey http://haveyoursay.gw.govt.nz/rivers-and-coast-users-survey has been extended until 13th May to allow people to comment on these results and to get feedback on how, when and where people enjoy the region's rivers and coasts, and what they think about the quality of water.

The Council is keen to hear from all ages and there's an opportunity to enter the draw for a 3SIXT HD Sports Action Camera or an iPod Shuffle and Bassburger pocket speakers.

Final reports on recreational water quality over the 2014/15 summer will be published in June.

Key to grades:

A - Very low risk (of illness)

B - Low risk

C - Moderate risk

D - Caution

F - Unsuitable for swimming

Photo caption: Princess Bay in Wellington City was one of the best spots to swim last summer (Photo credit: Juliet Milne)