Monday, February 26, 2024

Shortcomings in water quality monitoring flagged 

Neal Wallace
Under current system, it will be decades before any improvements can be confirmed.
Reading Time: 2 minutes

It will take another 20 years to determine if New Zealand’s water quality is improving without new investment in monitoring systems.

Research for the Our Land and Water National Science Challenge, published this week, found shortcomings with existing water quality data as current monitoring doesn’t sample rivers often enough to provide an accurate reflection of contaminant concentrations.

For example, if a river is monitored monthly and this routine monitoring coincides with above- or below-average rainfall for a couple of months, this will distort the average contaminant concentrations recorded.

The authors note that in mid-January the Parliamentary Commissioner for the Environment, Simon Upton, wrote to Minister for Science, Innovation and Technology Judith Collins, highlighting the risks caused by a lack of stable funding for monitoring freshwater quality.

“Funding needs to increase five-fold to enable more frequent monitoring or a shift in focus to monitoring fewer sites more frequently”, concludes the journal paper, published by the Nature Publishing Group in Scientific Reports.

The research looked at policy to reduce concentrates of phosphorus and nitrogen species, E coli and visual clarity.

Current policy aims to begin showing improvements within five years and bring waterways to a healthy state within a generation, around 20 years.

“Our work suggests that demonstrating the outcomes of implementing policy for water quality improvement may not occur without a step change in investment into monitoring systems,” the report concludes.

Professor Rich McDowell, a chief scientist at Our Land and Water and an author of the paper, acknowledged that community groups, famers, iwi, and councils are working to restore the health of our rivers, lakes and groundwater.

But progress may not be evident.

“Our ability to link these on-farm actions with improvements in water quality is limited by our monitoring network,” he said. 

Dr Olivier Ausseil of Traverse Environmental and leader of the research programme, said existing fixed monitoring locations and frequencies can take a long time to detect improvements and to establish a link between cause and effect.

“For example, a group of farmers may be making changes to their farms to reduce nutrient losses to streams passing through their farms, but if the closest monitoring site is downstream in the flow of the main river, it may not detect any improvement.” 

The analysis showed NZ’s current freshwater monitoring regime could, on average, detect change in nutrients and clarity in 20 years for over 95% of monitored sites, but sampling needs to occur twice as frequently to detect changes in E coli within that period.

That would require a four-fold increase in the annual cost of sampling.

To detect change in five years would require up to five times as many samples, increasing the annual sampling cost by 5.3 times. 

The report suggests a focus on a mix of sites where changes in water quality occur rapidly and which are representative of long-term land use. 

“Our analysis isn’t a criticism of the existing monitoring networks, and we don’t suggest that high-frequency monitoring should be implemented everywhere,” Ausseil said.

“However, it does illustrate that getting both monitoring locations and frequencies right is critical if we want to confirm whether local freshwater restoration actions are working.” 

The research team has created a tool to help catchment groups, farmers, iwi and local and central government design freshwater monitoring programmes to detect improvements in water quality in response to freshwater restoration.

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