"However, we recognise the importance of recreational water users being well informed about the potential health risks at these sites, and that is why we have this programme.
"Weekly water samples from each site are sent to an independent accredited lab for testing. Results are received within 48 hours and are updated weekly on Horizons' dedicated Safe Swim Spots' webpage. There, an interactive map shows each of the swim spots marked by a red, amber or green location maker to indicate that week's bacteria results."
Horizons science and innovation manager Abby Matthews said the traffic-light system used is part of the Ministry of Health and Ministry for the Environment guidelines that provide guidance to councils and district health boards regarding how they should act when certain levels of indicator bacteria or algae are detected.
"For our lakes and rivers, green/should be safe to swim is when a sample is less than 260 E. coli per 100ml, amber/could be a health risk is 261-550 E. coli per 100ml and red/avoid swimming is greater than 550 E. coli per 100ml," Ms Matthews said.
"If a site falls into the red category, information is provided to the public that the site is considered unsuitable for recreational use.
"Gravel bed river sites and lakes are also tested for cyanobacteria, which is an algae that can be toxic. Horizons will be keeping an eye on this during summer and also reporting these results on the website. However, we do urge that the public and their animals stay out of the water if they are at a river and see black mat-like slimy growth on the stones that may also be musty smelling."
Ms Matthews said the results from the monitoring programme are used to help inform the council's work programmes and policies.
"The swim spot results help us identify areas that need some extra work and where improvements are happening. For example, water quality trends across the region for January 2007 to December 2016 show an improvement in E.coli trends at 17 per cent of 56 sites and 0 per cent declining.
"The Manawatu River, which is often thrust into negative limelight, is showing a 19 per cent improvement for E.coli. Horizons was also recently awarded a New Zealand River Award for the Whangaehu River due to improving E.coli trends.
"Looking at regional sites again, total oxidised nitrogen is improving at 35 per cent of sites with 2 per cent declining. Dissolved reactive phosphorus is improving at 22 per cent of sites and 7 per cent are declining. By identifying these declining sites we can better target management interventions such as reducing hill country erosion through our Sustainable Land Use Initiative, and improving the quality of our wastewater discharges."
Mr Gordon said in addition to their own website, Horizons' 80-plus monitored sites can also now be found alongside New Zealand's 16 regional and unitary councils' data on Land, Air, Water, Aotearoa's (LAWA) new "Can I swim here?" website feature.
LAWA is a collaboration between the councils, the Cawthron Institute, and the Ministry for the Environment, with support from the Tindall Foundation.
"We hope our monitoring programme, and campaign that we run over the same period, will reinforce the message that throughout summer most of our region's popular swim spots are safe for swimming," Mr Gordon said.
"We also hope that it will dispel some of the myths, such as rivers should be swimmable 100 per cent of the time. Unfortunately natural occurrences, such as high flows and floods, means this will never be the case.
"Water quality is just one factor in a number of potential health risks. We ask the public to be aware of hazards such as unstable banks and cliffs, submerged logs, and tsunami warnings and rips at beaches.
"Another thing to remember is that as sampling is weekly, the results may not always reflect the water quality for the whole week, especially if it has rained. A general rule is if the water looks clear and it's three days after rainfall, you should be good to go.
"Fingers crossed that unlike last season we get a long, hot summer this year and there are plenty of opportunities for people to get out and enjoy our fabulous swim spots."
Swim and win:
• Horizons swim spot campaign includes the competition Swim, Splash and Share Your Region, which encourages the public to post a photo of their favourite swim spot along with the hashtag #swiminourregion and the site's location tagged to Facebook, Twitter and Instagram. Entries are automatically in the draw to win a $1500 adventure package.
• Last year's winner is taking her class whitewater rafting down the Rangitikei River next week.
