Good work stops decline in waterways, but no improvements yet
An annual update of river water quality data on the LAWA (Land, Air, Water Aotearoa) website reveals that, in Southland, there has been little change in water quality over the last 10 years.
Environment Southland chief executive Rob Phillips said, while it’s positive that our monitoring isn’t showing further decline, it’s improvements we need to be seeing now.
“The analysis suggests that the ongoing work to improve land management practices is helping to halt further decline, but it’s not getting us far enough to see improvements. This information reinforces the need to do more,” Mr Phillips said.
“There’s a lot of work being done in the catchments across Southland, but we need to continually innovate and change our practices to ensure that we can improve the hauora, or health and resilience of our waterways.”
The river water quality data has been updated on the LAWA website and provides information on six indicators of river health, across four different land cover types. Southland’s results align with the national picture where water quality is generally best in rivers and streams running through catchment with native vegetation, and poorer water quality coming through the more modified areas like pasture and urban land cover. Indicators measured at each site fall into a band, from A (good) to D or E (poor).
- Of the 61 sites monitored for E. coli, just 10 fall into A and B band, suggesting these sites would be suitable for swimming based on the long-term monitoring grade.
- Macroinvertebrate monitoring shows the lowest scores come in the pasture covered land with 18 of the 57 sites in the D band and none in the A band. The number of sites below the bottom line (D band) has been increasing overtime.
- For ammonia toxicity and nitrogen, the picture is a little better. None of Southland’s sites fall into the D band, and around half are classified in the A band for both indicators.
- Dissolved reactive phosphorus results show 40% of sites fall into the A band, with the other 36 sites falling evenly across the B, C and D bands.
- For suspended sediments, of the 36 sites 14 are in A band (7 in pastureland cover and 7 in native vegetation land cover).
“We don’t have all the answers yet, but we’ve definitely made solid progress. By improving the way we manage our land, cutting pollution from our businesses and homes, and by working together, we can find practical, innovative solutions to improve our environment for future generations,” Mr Phillips said.
“We are drawing together the latest environmental science, regional economic analysis, Ngāi Tahu mātauranga (knowledge) and local input to work out how to achieve what we all want, and meet our responsibilities as set out in legislation and regulations. Our focus is on what we can achieve in the next 10 years,” Mr Phillips said.
The LAWA website shows the most up-to-date water quality data for rivers and streams monitored by regional and unitary councils, and National Institute of Water and Atmospheric Research (NIWA). Here New Zealanders wanting to learn about local river water quality can explore the state and trends of monitored waterways in their catchment: www.lawa.org.nz/explore-data/river-quality.
LAWA is a collaboration between New Zealand’s 16 regional and unitary councils, Cawthron Institute, and Ministry for the Environment, with support from Department of Conservation and Statistics New Zealand.
This evaluation requires an almost complete history of monthly measurements over the previous five years before a grade can be assigned, so not all sites that feature on the LAWA website can be graded. The ‘current state’ for 2020 at each site is based on data over the last five years (from 2016 to 2020).
The six key indicators reported on at the national level for the LAWA River Water Quality National Picture Summary 2021 are widely recognised indicators of river health and are reported against national guidelines. At an individual site level, LAWA shows more information including additional river health indicators.
The NPS-FM 2020 requires management of nutrients to protect the ecological health of waterbodies and LAWA will be reporting further on this as more data and reporting guidance becomes available.
Macroinvertebrate Community Index
Dissolved Reactive Phosphorus
Clarity (Suspended sediment)