The Bush administration is to blame for last fall’s die-off of 33,000 salmon along the Klamath River in Northern California, biologists from the state’s Department of Fish and Game have determined. They say the fish kill — the largest ever recorded in the West — was the result of the administration’s decision to divert water from the river to farming interests, a move that was heavily protested by environmentalists, tribes, and some in the fishing industry, who predicted that salmon would suffer as a result. At the time of the die-off, the Bush administration said not enough science was available to determine its cause; now, California biologists say they’ve done the necessary research and the conclusion is clear. They also noted a “substantial risk” of more kills if the government continues to divert water from the river. The U.S. Fish and Wildlife Service declined to take a stand on the California findings, saying it would conduct its own investigation. But Troy Fletcher, executive director of the Klamath-based Yurok Tribe, suggested that there was no need for further studies: “It’s not rocket science: Fish need water.”