The Yellowstone is America’s longest undammed river.
黄石河是美国最长的没有堤坝的河流。
2
Scenic river designations for the Delaware, White Clay, and other rivers will ensure that these rivers remain undammed forever.
这些自然野生风景区的称号将确保特拉华河、怀特克莱河等河流永远不会被筑坝的破坏。
3
However, in the four decades since thebuilding of the Glen Canyon dam, just upstream of the Grand Canyon, the onlysediment that it has collected has come from tiny, undammed tributaries.