Environment Canterbury carries out water quality monitoring at 10 sites in the Waitaki catchment, issuing the results on its website along with suitability for swimming.
The aim is to give an indication about the state of the sites in terms of the health risk from exposure to microbiological contamination, such as faecal coliforms.
It highlighted sites where people should be more careful about activities that involved direct contact with water.
It was a precautionary approach to managing public health risks and did not represent an overall picture of water quality in the catchment.
The results also represented tests taken on a particular day, and these could vary if there had been recent heavy rain or by other factors such as the presence of stock.
In the Waitaki Valley, most test sites rank fair and above.
Two ranked ''poor'' in the last testing: Loch Laird below the Benmore dam and Lake Benmore at the Glenburn Motor Camp.
That ranks them not always suitable for swimming, especially if there are signs of pollution, such as discolouration, or smells and they should be avoided after rain for up to three days.
Only one was at the top ''very good'' ranking, Lake Ruataniwha at the rowing headquarters.
In the ''good'' bracket was the Hakataramea River at State Highway 82 bridge, Lake Benmore at Sailors Cutting, Lake Ruataniwha at the camping ground and Lake Tekapo at Camp Beach.
''Fair'' was Lake Aviemore at Waitangi, Lake Benmore at Pumpkin Point and Lake Middleton.
Tests are carried out regularly and rankings reassessed.
Rankings
Very good - Suitable for swimming for almost all of the time.
Good - Suitable for swimming for most of the time. Swimming should be avoided during or following heavy rain.
Fair - Suitable for swimming, but avoid during or following rainfall or if there are signs of pollution, such as discoloured water, odour, or debris in the water.
Poor - Not always suitable for swimming. During dry weather conditions, ensure it is free of signs of pollution, such as discoloured water, odour or debris in the water, and avoid swimming at all times during and for up to three days following rainfall.
Very poor - Often unsuitable for swimming, recommended to avoid these sites.
Warning - Do not swim or allow dogs to have contact, usually relates to presence of toxic algae.
Waitaki Lakes water site: http://maps.ecan.govt.nz/WaterQuality
