For decades before it was selected for closure, the Treasure Island Naval Station in San Francisco Bay overhauled military ships and housed nuclear war academies that used radium, plutonium, and cesium 137 in their training courses. The Navy knew for years that those materials were not always in safe hands. But it did not acknowledge that history publicly, and as a result, workers preparing for civilian redevelopment may have inadvertently spread radioactive material around the island, The Center for Investigative Reporting (CIR) has found in a year-long investigation co-published by the Bulletin of the Atomic Scientists on its open website, www.thebulletin.org, and here in its subscription journal. With the naval station decommissioned, the city of San Francisco has set its sights on erecting a second downtown on Treasure Island, with plans for apartments for 20,000 residents, commercial development, and open space. But the CIR investigation—based on wide-ranging document reviews and interviews—has confirmed the detection of significant levels of radioactive contamination on the island during preparations for redevelopment. Rather than conduct a more systematic radiation survey, CIR reporters found, the Navy engaged in bureaucratic warfare with health regulators and joined the city of San Francisco in telling 2,000 civilians already living on the island that they need not worry about exposure.