Monitoring our waterways
Monitoring what’s happening in our environment is an important role of any regional council. Our scientists have several freshwater monitoring programmes in place as part of our State of the Environment reporting. These include:
Rivers and streams
We run two programmes for rivers and streams - water quality monitoring and ecological-monitoring. When the results from the two programmes are combined, they indicate the overall health of a river or stream.
1. Water quality - monitored at 60 sites in 49 rivers and streams in Southland.
Sites are visited monthly and samples/measurements are taken for both the physical properties (such as pH, temperature, and visual clarity), and the chemical characteristics (such as nutrients and dissolved oxygen). In addition, high flow sampling is carried out at key monitoring locations at the bottom of our major catchments to understand how much of a contaminant (including sediment and nutrients) is transported during high flows. Some of these key monitoring locations have continuous (every 10 - 15 min) records.
2. Ecological monitoring - involves monitoring the ecological health of our rivers annually at between 65 - 80 sites during late summer. In addition a subset of 30 sites is monitored monthly. The amount and type of slime algae on the bottom of the river bed (called benthic periphyton) the macroinvertebrates (e.g. insect larvae, worms and snails) and an assessment of habitat quality are some of the indicators recorded.
Lakes and Lagoons
We regularly monitor indicators of water quality in Lake Te Anau, Lake Manapouri and Waituna Lagoon, Lake Vincent, Lake George, and the reservoir). Check www.lawa.org.nz for monitoring data on these sites.
Our scientists have established 29 groundwater zones for managing groundwater resources in Southland. Groundwater levels are measured continuously in 21 different bores throughout the region. Groundwater levels are also measured in a further 86 bores every three months. Groundwater quality across the region is monitored via our sampling programme. Samples are taken every three months from 31 bores and analysed for a wide range of parameters including nitrogen, phosphorus and E.coli.
View information on groundwater zones and current groundwater levels at www.lawa.org.nz.
Scientists have found that Southland’s water quality has been declining in intensively farmed lowland catchments throughout the region.
The results of monitoring and targeted investigations have identified the following key issues:
- Rivers and streams in the developed areas of Southland generally have high levels of sediment, nitrogen and phosphorus. These levels are some of the highest in the country, as are nitrogen levels in groundwater.
- Sediment and faecal bacteria levels across the region are also high from a national perspective.
- Nitrogen levels in both groundwater and surface water are increasing over time.
- The most sensitive parts of the catchments (the estuaries, lagoons and coastal lakes) are showing signs of stress. Ongoing measurements have found that the estuaries and lagoons in the region are rapidly deteriorating due to excess sediment and nutrients. This includes three of the region’s main river catchments (Jacobs River Estuary, New River Estuary and Waiau Lagoon).
Future monitoring – building on our knowledge base
We are currently investing in a comprehensive science programme to build upon existing monitoring programmes. This will allow us to better understand Southland’s waterways and how they respond to pressures from different land uses.
Find out more about the Southland Science Programme.