Water work recognised at awards

The Mangere Stream west of Whangarei, ranked the poorest regionally for many water quality indicators in 2006/07, has been judged the most improved waterway in Northland. Photo / Supplied

Mangere Stream catchment earns Northland award with judges acknowledging 'huge improvement' in water quality.

Dairy farmers in the 8200ha Mangere Stream catchment west of Whangarei can take a bow. Their efforts helped get the stream named as Northland's most improved and the fourth equal most improved river nationally.

The benefits of upgrading farm dairy effluent treatment and excluding cattle from waterways were highlighted at the annual New Zealand River Awards in Wellington sponsored by the Morgan Foundation.

The Mangere Stream -- one of the five priority catchments in the Northland Regional Council's Waiora Northland Water programme -- received a 'regional award", given to the most improved river in each region assessed by their phosphorus content, which at high levels can promote the growth of algae and slimes, which smother other freshwater life and cause water quality issues

Judges said phosphorus levels in the Mangere Stream had been reduced by 14.5 per cent annually over the past 10 years, a huge improvement as the stream ranked the poorest regionally for many water quality indicators in 2006/07.

Since 2007, most farmers bordering the stream -- including Shayne O'Shea, of Kokopu, and his sister, Charmaine, who won the Ballance Farm Environment Award supreme 2013 award in Northland -- have excluded stock from waterways. Median concentrations of E.coli have decreased 14 per cent on average annually over the past seven years, which is associated with upgrades to 17 of the 19 dairy farm effluent systems in the catchment.

Northland Regional Council environmental management committee chairman Joe Carr said the award gave extra impetus to a Mangere catchment group co-chaired by dairy farmer Royce Kokich and iwi representative Tania Pene.

"The reduction in phosphorus levels in the Mangere Stream is largely due to measures put in place by farmers on surrounding dairy farms over the past decade or so, including substantial and costly upgrades to farm effluent systems and fencing and planting of riparian edges," Cr Carr said.

The three waterways ranked ahead of the Mangere Stream nationally were the Waimakariri River in Canterbury with a 37.8 per cent reduction in phosphorus levels, the Oroua River in Manawatu with a 19.6 per centdrop and the Cam River in Canterbury with a 19 per cent reduction.

Data on freshwater quality in Northland is on the website: www.lawa.org.nz/explore-data/northland-region.