When road and pipeline projects are proposed for Brazil’s Amazon, green groups here often object, citing the well-documented danger that developmental inroads will invite colonization and, thus, ever-more rainforest destruction.

Such is the case with the 324-mile (522-km), US$380 million natural gas pipeline that the state oil company Petrobras hopes to build in Rondônia state, from its Urucu field to the city of Porto Velho. Green organizations warn the project could touch off a devastating land-settlement stampede.

But there are exceptions—among them, a seemingly similar Petrobras project slated for Amazonas state. It calls for construction, at the same cost, of a 260-mile (417-km) gas pipeline through mostly virgin Amazon rainforest from the city of Coari to Manaus.

The Coari-Manaus project won preliminary approval last month from the Amazonas state environment secretariat’s enforcement arm, Ipaam, thanks largely to a determination by key officials that the pipeline will not become a conduit for colonization.