No.14 2005

Managing dairy farm drainage pollution
Dr Fleur Matheson (NIWA) monitoring a range of treatments involving wood chips, reed-sweet grass, and raupo, at the Te Hoe site.
NIWA research for Dairy Insight is starting to provide good detail on the effectiveness of constructed wetlands and wood-chip filters in removing pollutants in dairy farm drainage.
Our key finding to date is that, without the addition of treatment supplements, constructed wetlands probably need to be between 2 and 5% of the catchment area to give effective nitrate removal.

Getting the best out of hump-and-hollow farming
NIWA is working with the New Zealand Landcare Trust on a project looking at ways to minimise nutrient runoff from West Coast land conversions.
Farmers around Lake Brunner often create a series of long ridges and valleys (humps and hollows) across their fields to cope with high rainfall and improve drainage.

Water resources outlook (November - January)
The following soil moisture levels & river flows are likely:
North Island
Normal soil moisture levels and river flows
South Island
Below normal soil moisture levels and river flows

Water quality in Pigeon Creek
Last year, the Inchbonnie (Lake Brunner) catchment became the fifth study catchment in a project funded jointly by the New Zealand dairy industry and MAF’s Sustainable Farming Fund. The project is a long-standing dairy industry initiative and highlights best management practices for sustainable farming.
The five catchments are:
Toenepi Stream (Waikato)
Waikakahi Stream (Canterbury)
Bog Burn (Southland)
Waiokura (Taranaki)
Inchbonnie
The Inchbonnie catchment has an area of 600 hectares and drains to Pigeon Creek.

Water resources review (August - October)
River flows
River flows were normal to below normal over most of the North Island, except in Manawatu and Rotorua where flows were above normal. River flows were below normal to far below normal in Wellington and everywhere in the South Island, including the lowest seasonal flows on record for some rivers in Wellington, Marlborough, Tasman, and Otago.
[Water resources information provided by NIWA field teams, regional and district councils, and hydropower companies.]