At the western mouth of the Coorong, the Murray finally arrives at the ocean. Salt and fresh water mingle in the Goolwa estuary, a place the Ngarrindjeri have known and named for thousands of years. They are one of some thirty to forty clan-groups that lived across this region before British settlement, and remarkably, the only Aboriginal people whose country lay within 100 kilometres of an Australian capital to survive as a distinct, recognised nation. In 1994, a group of Ngarrindjeri women elders made an extraordinary statement: the island was sacred to them, bound up in knowledge passed only to initiated women, knowledge they could not reveal in public. A permanent link to the mainland, they said, would be as harmful as joining two organs of a living body. The waters needed to mix; the sky above them, including the Seven Sisters star cluster of the Dreaming, needed to stay open.

The claims became known, in the language of the dispute, as "secret women's business," and they collided with a development already years in motion. Adelaide developers Tom and Wendy Chapman had bought island land in 1977 for a marina, and the existing cable ferry could not serve their expanding plans. When the federal minister halted construction to investigate, the matter escalated through reports, courts, and headlines. Then other Ngarrindjeri women came forward to dispute the claims, and a Royal Commission ordered by South Australian Premier Dean Brown concluded in 1995 that the secret knowledge had been fabricated. The finding was devastating for the women who had spoken, and it hardened into common belief. But the women who asserted the sacred knowledge had refused to testify at all, holding that a public inquiry into restricted spiritual matters was itself a violation. They would not, even to defend themselves, hand women's knowledge to men.

What makes Kumarangk so difficult is that it forces a hard question: how do you prove a belief that is, by its own rules, secret? The Royal Commission saw fabrication. Others saw something stranger and more troubling. When the Howard Government passed a 1997 Act clearing the way for construction, and the bridge opened in March 2001, the story seemed settled. It was not. Later that year, Federal Court Justice John von Doussa heard the developers' damages claim and reviewed evidence the Commission never had. He found that the late emergence of sacred knowledge was exactly what one would expect of genuine restricted tradition, that the various accounts of the Seven Sisters story were consistent, and that he was not satisfied the women's knowledge had been fabricated. One museum expert who had testified against the women was found to have quietly been helping their opponents' lawyers.

The years since have bent toward the Ngarrindjeri. In 2002, redevelopment of the nearby Goolwa wharf unearthed the remains of an Aboriginal woman and child at a site the proponent women had described as a burial ground. The Alexandrina Council, which had let construction proceed, formally apologised and entered a Kungun Ngarrindjeri Yunnan agreement, the phrase meaning "Listen to Ngarrindjeri Speaking." On 7 July 2010, at the foot of the bridge, the Government of South Australia endorsed the finding that the secret women's business was genuine, and Ngarrindjeri elders led a symbolic walk across the span. They will use the bridge now, to reach their own land and waters. Culturally and morally, they still reject it. A theatre work titled Kumarangk, made by Ngarrindjeri women and guided by those who lived the events, now carries the story forward, told at last on Country and in their own voices.