Frans and Trudi Blom first brought the idea of conservation to the watershed in the 1950s by proposing that a section of the Selva Lacandona be reserved for the Lacandon Maya.

The first large hydroelectric project on the Usumacinta in "Boca del Cerro", Tenosique, Tabasco, was proposed in the 1980s, and would have stretched all the way up the Pasion and Lacantun tributaries, flooding Piedras Negras and Yaxchilan, among other known and unknown Maya sites.

Additionally, the Guatemalan journalist Victor Perera wrote about the river in The Nation and in his books, The Last Lords of Palenque and Unfinished Conquest, and Jan de Vos chronicled the region in his magisterial series of histories.

Ultimately the hydro project failed under the weight of its own disincentives: siltation, geology, seismic activity, distance from markets, politics, etc., but the outcry from conservationists, archeologists, writers, and the public helped.

Carlos Salinas de Gortari proposed a smaller but still monumental hydro project in 1990, and completed the periferico surrounding the Montes Azules reserve.

Articles in The New York Times and op-ed pieces by Homero Aridjis suggesting a binational reserve for the area, helped defeat this incarnation of the idea.

In the late 1990s, a consortium of scientists, and government and non-governmental organizations met in San Cristóbal de las Casas, under the auspices of the Wildlife Conservation Society and the University of Florida, to identify the extent and types of habitat remaining the region, and to draw maps of the watershed.

In Guatemala, the absence of the expelled CPR communities, which had helped keep the selva safe and secure, now left it open to invasion, illegal logging, smuggling of immigrants, arms, artifacts, and drugs.