The City Council has approved a new U.S. Army Corps of Engineers study on flood-control interventions for Wailupe Stream — the last waterway flowing into Maunalua Bay that’s not fully concrete-lined, and the only one still harboring native fish and shrimp. The study will cost $3 million, split evenly by the city and the feds.

The Corps has been here before — deciding in 2007 that a $40 million, concrete flood-control project would be more costly than effective. But “the Corps has evolved a lot over 20-something years,” public civil works chief Michael Salyer said, and will work with local stakeholders to develop a plan.