Unacceptable numbers of dairy and cattle stock still access and pollute many kilometres of riverbanks upstream of the Kaipara Harbour, says water quality campaigner Millan Ruka.
A recent Environment River Patrol's survey showed that along a 19km stretch between the Hikurangi wetland and Ngararatunua pump station on the Wairua River,at least 60 per cent of the bank was not fenced off from pasture.
Along a stretch where 2500 native plants were put in last August, 50 per cent had been eaten by cattle, Mr Ruka said.
Riverbanks continued to be degraded even after widespread publicity, education and campaigning about the harmful effect on water quality, native wildlife and downstream environments.
"The adverse effects are very apparent on this stretch of the Wairua River. It cannot be ignored that all this causes downriver effects on the Kaipara Harbour where 10mm of sediment is added each year and is suffocating the ecosystem of the moana."
Mr Ruka said he did not accept some farmers' arguments that they could not afford to fence all riverbank from grazing cattle. He has had support from Northland-based lobby group Farmers of New Zealand, whose spokesman, Bill Guest, scoffed at the notion that stock exclusion fencing was too expensive.
"If you had six coils of wire, for 1000 bucks, you can do a hell of lot of fencing," Mr Guest said.
Mr Ruka said he wanted the Northland Regional Council to consider funding hotwire fencing and setting up infringement fines for lack of fencing. At present, the regional council had no mechanism in place to fine farmers who "wilfully allow their cattle to pollute".
