Pine Harbour Marina Ltd will be allowed to continue to dredge the approach channel to the marina - but it won't be allowed to deposit the dredgings at a disposal site west of Flat Island (Motukaraka Island), near the channel entrance.

The marina company has been seeking new permits to replace its existing dredging consents, and an expired disposal consent.

It wants to continue maintenance dredging of the approach channel plus a 0.4 hectare area to the right of the marina entrance.

But its proposal to deposit the dredgings in the embayment at a 49 hectare disposal site, using a thin layer disposal technique, ran into opposition from the Pohutukawa Coast Community Association.

The PCCA says it has no problem with the marina's need to dredge, but believes depositing the dredgings in the embayment puts the local environment at risk.

The result was a resource consent hearing at the Auckland Regional Council chaired by commissioner Leigh McGregor.

The commissioners were satisfied with the dredging method and experience of the contractor and gave consent to dredge up to 3000cu3 a year from the channel, and the "delta area" by the marina entrance.

But the majority view of the commissioners was that some of the copper (from boat anti-fouling) in the marina basin was flushed out to sea on the ebb tide

"...exported material is a major contributor to the elevated copper levels found in the access channel. As a result, the finding the majority has reached is that Pine Harbour Marina Ltd should be required to dispose of its dredgings elsewhere..."

A minority view among the commissioners was that there was not enough evidence to suggest the marina was responsible for contamination of the channel sediment and that, because it did not cause the sediment, "...it should be permitted to move the material elsewhere in the same embayment from which it came."

The commissioners also ruled that the plume that can be seen when dredging is underway is not a serious concern, and that there is little evidence of dredgings affecting marine life at the disposal site.

But the commissioners did conclude that ...if the contaminated sediments were to be added to the disposal area, even in a diluted state as proposed, there may well be adverse cumulative effects on biota in either the long or short term, at both the Disposal Site and beyond"

The commissioners also ruled against disposing dredgings from the "delta area" - the site next to the marina entrance - in the disposal area.

"...we were persuaded that the level of copper contamination in the delta area sediment exceeds the ARC green guideline for the disposal of sediment to the coastal environment...the level of contaminants, particularly the elevated copper levels, in the delta area sediment is such as to preclude disposal of this material in the embayment."

A number of submissions asked for the approach to the public boat ramp at the marina be dredged but the commissioners ruled that the ramp falls outside its jurisdiction.