PEOPLE POWER: SAVING MANGAWHAI HARBOUR
This February, locals celebrated a milestone in Mangawhai’s environmental history.
It’s been 35 years since the legendary Mangawhai Big Dig, a monumental act of community defiance that rescued a dying waterway from environmental collapse. For locals, the Big Dig remains a defining victory of people power over red tape, proving what a community can achieve when it refuses to take no for an answer.
The Big Dig led directly to the formation of Mangawhai Harbour Restoration Society (MHRS), which partnered with coastal engineers to transform a rebel action into a world-class restoration and sandspit stabilisation programme. Today, they work alongside councils, Te Uri o Hau, DOC, and Mangawhai Matters to protect the harbour and the sanctuary of endangered shorebirds.
However, Mangawhai Sandspit is again under threat. Recent LiDAR surveys reveal a loss of 420,000 tonnes of sand in just six years. Experts warn this could lead to another breach within 15 years. As the primary guardian of the harbour’s delicate equilibrium, MHRS continues the mission started by the Rebels, ensuring this vital legacy of stewardship endures.
The crisis began in 1978 when a violent storm tore a 600-metre breach through the southern end of Mangawhai Sandspit. By the late 1980s, the breach had become nearly unnavigable, and the harbour mouth had choked completely, halting tidal circulation and causing the estuary to stagnate. Faced with institutional paralysis, a band of ‘Big Dig Rebels’ refused to let the harbour fail, taking direct action to restore the water’s vitality.
At 6am on 11 February 1991, more than 100 locals staged a historic intervention, using 40 heavy machines to carve a small new channel and reopen the harbour entrance. In just four days, and without legal consents, they restored tidal flow. The struggle continued for the next five years, as dedicated locals used old dredge machinery under challenging conditions, keeping the water flowing while rebuilding the rock groyne at the harbour entrance.
The turning point came when formal Resource Consents were finally granted in 1995, allowing dredging of the lower channel and repurposing sand into a permanent bund wall. This closed the rogue breach in 1996, establishing the stable inlet Mangawhai enjoys today.