A total of six Hawke's Bay sites have been given a "very poor" rating by a national report outlining the suitability for swimming in New Zealand waterways.
The report, along with another reviewing river quality conditions, was completed by the Ministry for the Environment this week. The indicator reports were used as an avenue to inform the public on water quality for recreational activities and the health of rivers.
The indicator report provided a summary of monitored swimming sites and reflected a precautionary approach to managing public health risks. Even a very small risk would be flagged through a lower grading.
Hawke's Bay Regional Council said six coastal sites in the region had been flagged as having the best suitability for swimming.
These included Aramoana, Blackhead Beach, Ocean Beach, Porangahau Beach, Pourerere Beach and Westshore Beach.
The indicator flagged six other Hawke's Bay sites as having "very poor" suitability for recreation.
These waterways included Lake Tutira, Clive River, Porangahau Estuary, Puhokio Stream, Waipuka Stream, and Waipatiki Lagoon.
Regional council senior scientist, coastal quality, Anna Madarasz-Smith said the "very poor" sites could be influenced by faecal contamination, which may come from rural or urban run-off, or dense populations of birdlife.
"Lagoons generally have a lower water quality because they are often shallow, with reduced water flow, warmer water and attract birdlife.
"Lake Tutira has had persistent problems this season, most notably algal blooms that were present for much of the summer."
Minister for the Environment Amy Adams said the river condition indicator was based on data collected across more than 300 regional council and NIWA-monitored sites over a 10-year period (2000-2010), out of the tens of thousands of waterways across New Zealand.
The report showed overall concentrations of nutrients and bacteria were either stable or improving at most monitored sites, and water quality was generally improving.
The swimming suitability indicator showed many swimming spots were affected in wet weather as a result of stormwater run-off. At some sites, heavy rain and wind can churn up sediment from the bottom of the waterway, releasing pathogens back into the water. Other common sources of water pollution are urban stormwater systems, livestock, fertilisers and dense populations of wildlife.