Horizons Regional Council is currently below the national average for swimmability, but improvements are occurring.
The regional council has set their swimmability targets for the region's large rivers and lakes suitable for swimming at 70 per cent by 2030 and 80 per cent by 2040.
And for the summer, when most people actually swim, the regional council has set a target of 90 per cent by 2040.
"Council is already reviewing its approach to fresh water and this includes proposed One Plan changes," Horizons chairman Bruce Gordon said.
Modelling for the Ministry for the Environment estimates work already planned will see the length of rivers in the region suitable for swimming increase from 43 per cent to 60 per cent over the 12 years to 2030.
"While this modelling does not take into account factors such as climate change, economic or social drivers, or future changes to policy, council has agreed to aspire to higher targets of 70 per cent by 2030 and 80 per cent by 2040," Gordon said.
"Council are aware that significant investment will be needed to meet targets higher than the current modelling predictions, however, we recognise our communities aspire to better water quality and we have set ourselves ambitious targets.
"While our region is currently below the national average for swimmability, we are seeing a faster than average improvement. Our Sustainable Land Use Initiative (SLUI), which targets erosion prone hill country, and our Freshwater programme, assisting farmers and community groups with fencing and planting, are beginning to make a difference.
"Further interventions and their associated costs are yet to be explored. However, we already know that taking a planned, whole of catchment approach and prioritising effort and investment where it would make the most difference, works.
"Additionally, Horizons' non-regulatory work programmes, the commitment from our territorial authorities to upgrade wastewater treatment plants and manage stormwater better, landowners investment in environmental improvements and efforts of community groups will all contribute to improved outcomes for swimmability and overall water quality."
Horizons natural resources and partnership group manager Dr Jon Roygard said in 2016 the region council upgraded its swim spot monitoring programme from 17 spots to 83 throughout the region.
"From early November until the end of April samples are taken from these sites on a weekly basis and sent to an independent and accredited laboratory for testing.
"They are tested for faecal indicator bacteria including E. coli for freshwater and Enterococci for coastal waters. Our scientists also check each site for phormidium, known as potential toxic algae or cyanobacteria," he said.
"The bacteria and cyanobacteria results are made available to the public on Horizons and Land Air Water Aotearoa (LAWA) websites, so that they can make an informed choice and about when and where to swim in our region."
Roygard said there is still work to do to improve the swimmability of the region's rivers and next step will be to plan and undertake actions to work toward the achievement of the new targets the regional council has adopted.