The vote came despite developer Steve Harmsen's state water quality permit from the Federal Energy Regulatory Commission.
What led the Idaho Land Board, composed of Gov. Phill Batt, Secretary of State Pete Cenarrusa, Attorney General Al Lance, Controller J.D. Williams and Superintendent of Public Instruction Anne Fox, to stop a seemingly unstoppable hydroelectric project?
"This has national implications because I've never heard of a licensed hydro project being turned down before," says Laird Lucas, an attorney based in Boise with the Land and Water Fund of the Rockies.
The board cited the public trust doctrine in denying the dam, which would have dewatered seven rapids to produce 43.6 megawatts of electricity. All of the power would have been shipped to Utah.
Dating back to the ancient Romans and written into the Magna Carta, the public trust doctrine holds that natural phenomena such as flowing water are held by the state for the benefit of all. Its most significant application in the West came in 1983, when the doctrine was used to bar Los Angeles from exercising its vested water rights to drain Mono Lake.
More than anything, the board's decision represents a major change in the attitude of local citizens about this "working" stretch of the Middle Snake River, which already accommodates seven dams. For decades it has been diverted for irrigation, leaving what remains sluggish and heavily laced with dirt, farm chemicals and other industrial pollutants. Algae grow thick in the river.
Twenty years ago, the citizens of Twin Falls, Jerome and other local agricultural communities would not have voiced much opposition to the project, says Roy Prescott, a county commissioner and rancher in Jerome. But the dire condition of the river has changed everything.
"Maybe we're at a point in time where we just say no - just because it's wrong," says Prescott.
At a public hearing about the hydro project this January, some 200 people turned out, but the only supporters were Harmsen, his consultants, and people from whom he's buying riverfront property. Liz Paul, staffer with Idaho Rivers United, said the hearing showed that "people want the Snake River to be healthy and (left) in good shape for their kids."
Auger Falls is important because for two miles the river flows freely at the bottom of a canyon 480 feet deep. Harmsen had agreed to let the city's sewer plant spill treated water onto 200 acres he owns; now, ammonia-tainted water gets dumped directly into the river, causing some boaters to rename Auger Falls, "Sewer Falls." Harmsen also offered to turn any remaining riverfront property into a public park and to stabilize eight miles of streambanks.
The developer, who lives in Salt Lake City, has said he will appeal Idaho's turndown, probably in court. He must resolve the issue quickly since his FERC license expires Aug. 31.
The writer covers natural resources for the Times-News in Twin Falls, Idaho.
Intern Jenny Emery contributed to this story.