Our beaches - 2010/11

In most places and on most days, our region’s beaches and rivers were fine for swimming last summer, Greater Wellington’s recreational water quality monitoring report for 2010/11 On the Beaches shows.

However, two coastal sites in Porirua exceeded the national recreational water quality guideline repeatedly, and in most cases rainfall was not a contributing factor. “Most sites only exceed guidelines after heavy rain as it washes contaminants from agricultural and urban areas into our waterways,” says Greater Wellington Senior Environmental Scientist Summer Warr.

The two sites of concern in Porirua were the Porirua Harbour at Rowing Club and Titahi Bay at South Beach Access Road which exceeded the action guideline on six and five occasions respectively. Although investigations by Porirua City Council staff into the cause of these exceedances have been inconclusive, sewer cross connections with the stormwater system are believed to be a contributing factor and are being investigated further.

Porirua Harbour Strategy Coordinator Keith Calder said the results were disappointing given the effort PCC has put into identifying and rectifying a number of contamination sources.

"Our council is dedicated to cleaning up the harbour. We've already investigated and rectified cross connections in the Kapiti Crescent catchment and are now looking at the Gloaming Hill area. We're pretty confident this work will make a major difference to the water quality near Onepoto. Work is also being carried out in the Titahi Bay South Beach area and we expect both sets of investigations to be completed over the next six months.”

“The summer’s monitoring results highlight that sewerage and stormwater infrastructure are potentially key sources of faecal contamination at our urban beaches. It is pleasing to see that Porirua City recognises this and is accelerating work on its wastewater network in its 2011/12 Annual Plan,” Greater Wellington Regional Council Te Upoko Taiao – Resource Management Committee Chair Chris Laidlaw said.

The recent swimming season has also highlighted that some of our rivers continue to have issues with the growth of potentially toxic blue-green algal mats (cyanobacteria). Health warning signs were posted at key access points along the Waipoua, Hutt and Waikanae rivers at various times during the summer to alert people of the risk from toxic algae and what precautions they should take.

Dogs are particularly at risk due to their tendency to scavenge around potentially toxic algal mats. In December, a dog died after coming into contact with the mats in the Hutt River near Melling.
See the full report at http://www.gw.govt.nz/Annual-monitoring-reports/

About Recreational Water Quality Monitoring in the Wellington region

Greater Wellington monitors recreational water quality in association with the Kapiti Coast District Council, Porirua City Council, Hutt City Council, and Wellington City Council, to help determine the suitability of different freshwater and coastal sites for recreation and to safeguard public health and the environment.

Water samples were taken weekly over summer (mid November to the end of March) at 77 coastal sites and 21 freshwater sites and tested for faecal bacteria* which indicate the potential presence of disease causing micro-organisms such as campylobacter, salmonella, cryptosporidium and giardia.

* E. coli (freshwater) and enterecocci (marine waters) are the bacterial ‘trigger’ values to help water managers determine when management intervention is required.