There are many questions that arise from the story of city crews depositing construction rubble along the banks of Ma'ili'ili Stream, but the essential query is this one:

Why did the city let this unpermitted action happen? Taxpayers must now pay to remove the debris and possibly federal fines or other penalties.

About a mile inland from Farrington Highway on the Wai'anae Coast, an eight-yard-wide blanket of rubble — mostly broken sidewalk pavement studded with rusting rebar — has been laid down. It's big and unsightly, stretching about 175 yards mauka.

The rubble should never have been placed by a stream, where its component chemicals could leach into the water and flow to the ocean. The debris also could be washed downstream in a heavy rain and block the flow.

All of these are reasons that a federal permit was required and should have been obtained. Now the Environmental Protection Agency has ordered all the debris removed and is investigating what happened; the city is doing its own internal inquiry.

The city's official explanation, issued in a prepared statement, is that the facilities maintenance crew was using the rubble as pavement to restore an access road servicing the stream and simply didn't know a permit was required.

But the public has a right to clearer answers than that. Who authorized the work, for example? How much was spent on depositing the debris on the stream bank? That's an expenditure that now will be compounded by the order to clear it all out again. And how much will it cost to correct the error?

The immediate duty of city officials is to deliver a cleanup plan to the EPA quickly.

However, they also are accountable to answer questions — from the City Council and other authorities, as well as the public — about how this happened and how the lack of oversight will be corrected in the future. Coupled with reports of other construction-debris dumping going on for years in nearby Wai'anae Valley, on Hawaiian Home Lands property, this episode has residents wondering about government's commitment to protecting the environment.

It's time for a clear and thoroughly public accounting of this unacceptable failure.