He said the regional council was not complying with its own best practice guidelines on forestry earthworks and harvesting, outlined in a handbook developed in collaboration with the forestry industry.
Regional council regulatory services manager Colin Dall said while the guidelines did not currently address forest planting or replanting, there were relevant new rules in the Draft Regional Plan.
It proposed that forestry planting would no longer be a permitted activity; instead requiring a resource consent if planting was within 5 metres of any permanently or intermittently flowing river or any natural wetland, 10 metres of the bed of any lake or significant wetland, 20 metres of the bed of any outstanding water body or within the coastal riparian management zone, Mr Dall said.
Both the existing and draft Regional Water and Soil Plan contained rules relating to earthworks and activities in water bodies including fords, culverts and bridge crossings.
Mr Dall said the council monitored consents and followed up significant non-compliance and complaints.
It was currently prosecuting two companies and an individual for alleged illegal forestry earthworks in the Ngawha area, he said.
Mr Miru said it was often too late, the damage was done.
"The regional council is the environmental watchdog and it is not doing its job."
Mr Miru, also a member of the regional council's Tai Tokerau Maori Advisory Committee, said the council could give iwi organisations a monitoring role.
"Under Section 33 of the Resource Management Act, the regional council has the power to give an iwi authority the role of statutory monitoring authority.
"I want Te Uri o Hau to take over the environmental responsibility within their rohe because nothing is happening on the part of the regional council, which does have the statutory obligation."
Mr Miru quoted Dr Mike Joy's work on the degradation of water quality and freshwater biodiversity in New Zealand. But, when asked, Dr Joy said he put slash fairly low on his list of water-quality issues and did not think slash in itself caused toxicity.
"Northland rivers are very susceptible to sediment and already you can see huge impacts in waterways and estuaries. I have deep concerns about NRC completely failing the environment, as have most of our regional councils, [by] emphasising short-term economic gains over long-term environmental bottom-lines."