Mangatarere Stream report – no dairy effluent storage

by Russel Norman

This is one of the more detailed reports into a river system – the Mangatarere. Put out by Wellington regional council yesterday.

The Mangatarere is in the Wairarapa and feeds into the Waiohine which feeds the Ruamahunga. It has some significant problems and the report tries to find out why.

I’ve only read the Summary, but a few things stand out.

Carterton waste water treatment plant add a fair bit of the phosphorous. But it is the dairy farms and a pig farm that add the nitrogen and e coli. The riparian mangement is pretty bad. Abstraction for irrigation is drying it out in summer, much more than it would naturally.

But here’s the kicker, only 6 of the 30 dairy farms in the catchment have storage for the dairy shed effluent. This is quite shocking. This means that even if it’s driving with rain and the ground is soaked, the effluent will be sprayed on the field because they have no capacity to store it.  So the raw effluent runs off the field with the rain and drains into the river, or if the ground is soaked it pools and runs off over the surface, or it soaks right through and passes into the groundwater.

That is pretty wildly bad state of affairs for the Wellington regional council which should be one of the better ones.