lower Snake River dams, leaving the Clearwater, Grande Ronde and Salmon river to sustain spawning salmon. Rising in several forks in the Clearwater Mountains of central Idaho, the Clearwater and Salmon River watersheds are nearly undeveloped with the enormous exception of Dworshak Dam on the North Fork Clearwater River. The watershed of the Grande Ronde in northeastern Oregon is also largely undeveloped. The four reservoirs formed by the lower Snake River dams—Lake Sacagawea, Lake Herbert G. West, Lake Bryan, and Lower Granite Lake—have also formed problems, as the downstream current in the pools is often not enough for the fish to sense, confusing their migration routes. At the confluence of the Snake and Clearwater Rivers, young salmon that swim down from spawning gravels in the headwaters of the Clearwater River often delay their migrations because of a significant temperature difference. (Prior to the removal of Lewiston Dam on the main Clearwater and Grangeville Dam on the South Fork Clearwater, the Clearwater was completely unusable by migrating salmon.) Agricultural runoff and water held in reservoirs higher upstream on the Snake warm its waters as it flows through the Snake River Plain, so as the Snake meets the Clearwater, its average temperature is much higher. Directly below the confluence, the river flows into Lower Granite Lake, formed by Lower Granite Dam, the uppermost dam of the Lower Snake River Project. Paradoxically, the combination of these factors gives the young salmon further time to grow and to feed in Lower Granite Lake, so when they begin the migration to the Pacific Ocean, they often have a higher chance at survival, compared to those salmon who migrate to the ocean earlier. Lower Snake River dam removal A controversy has erupted since the late 20th century over the four lower Snake River dams, with the primary argument being that removing the dams would allow anadromous fish to reach the lower Snake River tributaries—the Clearwater River, the Tucannon River and the Grande Ronde River—and spawn in much higher numbers. However, removal of the dams has been fiercely opposed by some groups in the Pacific Northwest. Because much of the electricity in the Northwest comes from dams, removing the four dams would create a hole in the energy grid that would not be immediately replaceable. Navigation on the lower Snake would also suffer, as submerged riffles, rapids and islands would be exposed by the removal of the