There's been a lot of talk lately about land use change and its impact on water quality in Southland. However, do we have any evidence that water quality is actually declining? The short answer is "yes". Scientific monitoring and investigations confirm that Southland has both water quality and quantity issues.
Rivers, lakes and streams are important resources in Southland and are highly valued by people for many reasons including for food collection and drinking water, disposing of wastewater, energy for hydroelectric power, and as place's for recreation. Increasingly, the ecological and aesthetic values of rivers, lakes and streams, the diverse ecosystems and life they sustain, are being recognised as well.
The health of rivers, lakes and streams is influenced by natural factors, such as climate, soil and rock type. However, human activities also play a major role, particularly what people are putting into the water, via both direct discharges and runoff from land, affecting the quality.
In Southland there are three main issues that affect water quality:
Sediment (e.g. mud and silt) - accumulates on the bottom of our rivers, lakes and estuaries. It is a problem because it can make the water murky, block fish gills, smother the habitat that macroinvertebrates and fish live in and promote slime algae growth. Sediment in streams can be generated from heavy rainfall on vulnerable soils, disturbance of the riverbed or bank by heavy machinery or stock or through direct discharges
Nutrients - particularly Nitrogen (N) and Phosphorus (P), which are needed by all plants to grow. The majority of nutrients come from stock urine/dung or fertiliser. However, too much N and/or P in our waterways causes problems with excess slime algae and aquatic plant growth.
Bacteria (e.g. E.coli) - faecal bacteria including E.coli are an indication of potentially disease-causing organisms that can make humans and animals sick.
What we are doing
Water is Environment Southland's number one priority. To respond to Southland's declining trends and to meet the requirements from central government, the council has developed the People, Water and Land programme.
People, Water and Land is an Environment Southland project to maintain and improve Southland's freshwater (including rivers, lakes, wetlands and groundwater). This project is in partnership with Ngai Tahu ki Murihiku and aims to maintain and improve Southland's water quality, ultimately helping the Southland community achieve its goals for our region's water. You can read more about this project and progress we are making here.
We also continue an extensive ongoing monitoring programme, which aims to help us better understand long-term trends in water quality, where contaminants are coming from and how we can best look after the quality of our waterways.
The 'Water Quality in Southland' factsheet provides a regional summary of water quality using both state (where it is currently at) and trends (how it has changed over time). Included is a comparison with several national bottom lines. In particular, E.coli, nitrogen, slime algae (periphyton) and macroinvertebrates (fish food) are presented to provide an overall picture of water quality in Southland.
For a broader view on Southland's freshwater resources, view the State of the Environment (SOE) report, Water 2010 Part 2: Our Ecosystems reports on the current state of our freshwater ecosystems and also the changes that have occurred over time. It attempts to answer the question: How healthy is the life in our water and our freshwater ecosystems?