A man from Whangarei who has been filming the pollution of local rivers says he plans to put his photographs and videos online.
Millan Ruka has bought a boat and film gear to patrol rivers he swam and fished in as a child, to show what dairy farmers are doing to them.
He says Northland Regional Council has shrugged off his detailed reports and told him there is little it can do.
Mr Ruka says putting the evidence online will allow people to judge for themselves and decide whether the council's rules are adequate.
He says in most cases, an electric fence would be enough to keep cattle out of rivers like the Whakapara and Wairua and stop them fouling and destabilising the banks.
Northland Regional Council says it does not have the resources to patrol rivers in the same way Mr Ruka is doing.
Regional council monitoring manager Riann Elliot says the council does test water at points along the rivers and knows that quality deteriorates with distance.
He says the council has written to each farmer whose cows Mr Ruka filmed, reminding them of their obligations under the Clean Streams Accord.
The Environmental Defence Society has asked to see the footage and says it may also refer Mr Ruka's reports to the Land and Water Forum, which is advising the Government on freshwater management policy.