BOISE — When the leaking face of the brand-new Teton Dam gave way on June 5, 1976, and 80 billion gallons of water surged down a valley of eastern Idaho farming towns, it left behind the lakebed, empty except for mud and debris from landslides as banks caved in.

Three decades later, hundreds of millions of dollars of community rebuilding have left few signs of the devastation downstream from the broken dam, where a wall of water moving at 15 miles an hour killed 11 people and swallowed hundreds of homes and 18,000 head of livestock.

Yet upstream from the earthen pyramid remnant of the dam, the drained bathtub of the Teton Basin remains unrestored, undeveloped and undiscovered.

A new study by the federal agency that built the defective dam finds many area residents prefer to keep it that way.

"We didn't hear what we thought we would, and that was a desire for developed recreation and more access," said Vicki Kellerman, a recreation planner for the U.S. Bureau of Reclamation in Boise. "What folks told us instead was they did not want to see big boat launches and campgrounds. They want to keep it the way it is."

The bureau's new environmental assessment for the Teton River Canyon is the first time since the dam burst that the agency has addressed the question of what to do with the drained reservoir. The so-called "mass wasting event" triggered 200 landslides upstream from the dam, located about 20 miles northeast of Rexburg in eastern Idaho near Grand Teton National Park.

Kellerman said the 30-year delay in considering the empty lake's future stems from indecision over the Teton Dam itself. Despite the disaster and two subsequent investigations that faulted Reclamation for siting an earthen dam in a valley of porous clay, some still want the dam rebuilt.

"After the failure, there was a lot of interest in rebuilding the dam. And with the drought we've had, there are still folks who would like to see it rebuilt because the needs for irrigation are still there," said Kellerman. "So, we've been in an extended 'hold' mode and finally decided if we are going to be responsible for managing those lands, we need a cohesive plan."

The less-than-enthusiastic reaction by residents in the downstream communities to any proposal to transform the Teton River Canyon into a developed recreation site reflects the segment of the population that still hopes to see the dam rebuilt, said author and Idaho historian Cort Conley.