That is the main point of a recent decision by commissioners who heard the City Council’s bid to continue using the estuary as the endpoint for its wastewater system.

The commissioners’ weighty report includes many decisions and conditions, but their main finding — that the estuary is no longer a suitable place to put treated effluent — effectively means the public, Council staff and Councillors must look again at how best to deal with wastewater.

Several articles in this issue of City Scene are dedicated to this topic.

The Council has not made a decision about what it will do next. It has directed staff to file an appeal against the commissioners’ decision to make sure it is keeping its options open and will spend the next few months reviewing those options and deciding what to do next. The decision to put in an appeal does not mean the Council will decide to ask the Environment Court to overturn the decision and allow it to go ahead with the estuary discharge plan.

In its application, the Council asked for approval to discharge into the estuary for 15 years on the basis that the water being discharged would be of bathing quality. The commissioners said the Council could have only five years of estuary discharge through its current outlets and that, within two years, it should build a bug-killing ultraviolet plant and have trickling filters operating to further remove nutrients from the wastewater.

The Council asked to be able to discharge up to 0.5 million cubic metres a day around high tide. The decision allowed this with some conditions.

Walter Lewthwaite, the Council’s senior projects engineer leading the wastewater project, says there was a fundamental difference between the way the Council saw the estuary and what the commissioners took from the evidence they heard and read.

“The Council looked at all the evidence from the experts and the studies done and saw the estuary as being in a modified-but-stable state,” he says. “The Commissioners saw it differently.

“Looking at the same information, they concluded the estuary is ‘degraded’, ‘over-enriched with nutrients’ and close to collapse environmentally. They therefore considered it is no longer acceptable to discharge treated effluent into the estuary and that this should over-ride any other plans from the Council.”

The five-year permission to keep discharging was made to give the Council the time needed to provide an alternative solution.