But the U.S. Bureau of Reclamation disagrees that 50 years is an advanced age for a dam.
但是，美国垦务局不同意大坝只有50年使用期的说法。
2
But the population of rare and unique fish species has been declining since the 1980s because of dam building, water pollution, overfishing and land reclamation.
Land reclamation technology includes surface humus soil stripping and piling, blocks the dregs dam. retaining dam, flood drainage guide, land leveling and backfilling of soil humus.