April Sall gazed out at the Mojave Desert flashing past the car window and unreeled a story of frustration and backroom dealings.

Her small California group, the Wildlands Conservancy, wanted to preserve 600,000 acres of the Mojave. The group raised $45 million, bought the land and deeded it to the federal government.

The conservancy intended that the land be protected forever. Instead, 12 years after accepting the largest land gift in American history, the federal government is on the verge of opening 50,000 acres of that bequest to solar development.

Even worse, in Sall’s view, the nation’s largest environmental organizations are scarcely voicing opposition. Their silence leaves the conservancy and a smattering of other small environmental organizations nearly alone in opposing energy development across 33,000 square miles of desert land.

“We got dragged into this because the big groups were standing on the sidelines and we were watching this big conservation legacy practically go under a bulldozer,” said Sall, the organization’s conservation director. “We said, ‘We can’t be silent anymore.’ ”

Similar stories can be heard across the desert Southwest. Small environmental groups are fighting utility-scale solar projects without the support of what they refer to as “Gang Green,” the nation’s big environmental players.