To understand the scale of change required to meet Murihiku Southland draft freshwater objectives, Environment Southland has undertaken modelling of the contaminants nitrogen, phosphorus, E. coli and sediment.
Modelling to date has tested eight of the objectives relating to eutrophication in rivers, lakes and estuaries (for nutrients), visual clarity in rivers (for sediment) and E. coli in rivers.
Find out more about each of the key contaminants we monitor, and some of the scientific modelling we've done to understand how much reduction is required to achieve our goals.
We have estimated the load reductions required to achieve the minimum state required to reach hauora and meet our draft freshwater objectives. Alternative outcomes are also modelled to provide context on risk. The table shows load reductions required to achieve water quality standards in the proposed Southland Water and Land Plan or to maintain current state. It also shows load reductions to achieve the National Bottom Lines for national compulsory attributes and the minimum acceptable state for Southland waterbodies (shown as ‘Bottom Lines’).
Regional reductions needed to meet targets | Total Nitrogen | Total Phosphorus | E. coli in rivers | Sediment |
| | | | River suspended sediment | River visual clarity |
National bottom lines
| 47% (33 – 61)
| 21% (13 – 33)
| 77%
| 24%
| N/A
|
Proposed Southland Water and Land Plan standards
| 66% (58 – 74)
| 69% (59 – 77)
| 82% (72 – 94)
| 24%
| 31%
|
Hauora - Draft freshwater objectives
| 70% (61 – 78)
| 70% (62 – 77)
| 90% (80 – 96)
| 24%
| 32%
|
Note: the numbers in brackets provide the top and bottom of
the 90% confidence interval. The figures use a 20% exceedance
criteria.
