Artificial intelligence using sensors for real-time monitoring and citizen science will play major roles in monitoring the public health safety of swimming spots, Stott told an agricultural and horticultural science conference.
Stott, a specialist in environmental health microbiology at NIWA, said the agency has been working on innovative ways to assess microbial contamination in water.
NIWA is working with farmers, regional councils and community volunteers to compare privately-gathered data with local government data to test and validate low-cost and easy-to-use methods for water-quality monitoring.
Sampling, testing and reporting the state of rivers and streams for swimming and other recreational use is notoriously laborious and often expensive.
Microbial contamination in the same stretch of water can vary minute to minute and the sheer number of possible test sites makes it hard to show more than a broad trend over days and weeks.
It typically takes at least two days to sample, test and report the results of sampling at a recreational swimming spot.
But those results are largely useless for the average spur-of-the-moment water user, though grading of sites using longer-term monitoring will provide an indication of the potential risk from swimming at that site.
Stott, speaking at a New Zealand Institute of Agricultural and Horticultural Sciences conference at Lincoln, said people have a broad view of what swimmability and recreational suitability mean for the community.
That includes a growing number of farmers keen to show how well they are managing land and water.
To determine the recreational suitability of water, a range of tools can be used to record periphyton, including cyanobacteria, E coli, visual water clarity and rubbish, Stott said.
NIWA is also updating its methods for SHMAK (stream health monitoring assessment kit) to support interest from farmers and other private users like school and community environment groups in water monitoring and reporting.
“When we look about in farming communities we also need to make sure that what we develop for them is fit for purpose. They want to be sure their data is robust and they want it to be used.”
The organisation is looking at ways to capture the community’s broader perspective of the information to create a multi-factor index of recreational suitability that can be used nationally.
At Stott’s Waikato base NIWA is also testing real-time microbial sensors and environmental proxies to build a more comprehensive picture of swimming suitability, using rapidly-detectable markers for faecal pollution.
That makes it easier to pick up why and when water is unsuitable for recreation because of leaking sewer infrastructure or rainfall washing in faecal contamination from livestock farming, for example.
To protect human health, the swimmability of freshwater is determined by the possible presence of pathogenic faecal micro-organisms while the amount of the bacterium E coli in water is used as the risk indicator.
The presence of periphyton and low visual clarity is also viewed by communities as a safety hazard as well as an aesthetic consideration.
“We know we have multiple influences on those contaminants. Sometimes they can be natural influences and if they’re natural it will be difficult to improve the water quality or conditions for recreational use so we will need to manage people’s expectations with that,” Stott said.
Red flags for water contamination include the presence of cyanobacteria, which, in rivers, can form nasty mats.
Stott said people often think of cyanobacteria as a risk to people though in the Hutt River and elsewhere, dogs had died after contact with growths that were exposed after river levels dropped. Recreational guidelines for cyanobacteria are being updated by Nelson-based Cawthron Institute with help from NIWA.
Managing faecal microbial contamination from livestock farming tends to focus mostly on flat land, using systems such as wetlands to intercept and treat pollution before it gets into waters.
But managing for microbial discharges from steep hill country, where sheep can shed a lot of campylobacter – a pathogen risky for swimmers – has been largely neglected and needs to be urgently addressed in to improve downstream water quality, Stott said.
