The U.S. has more than 87,000 dams greater than six feet high (and two million overall). While many dams continue to provide benefits such as flood control, irrigation, and water supply, for other dams the cost of maintenance or the negative effects on communities, fish, and tribes justifies their removal.
Dam owners and regulators decide whether to remove a dam by weighing many factors including: the cost of removal and the ability to replace any lost power generation against avoided long-term maintenance; safety concerns; benefits to endangered fish populations; increased recreational and commercial fishing; and restoration of cultural values of nearby tribes.
By 2020, roughly 70% of dams will be more than 50 years old, inviting us to reconsider the value to the public of long-term investments in this infrastructure.
Because with maps they knew where to go , without them they will be lost
Answer:
In a federal system there is no centralized authority, while in a confederal system power is distributed equally among the states.
Explanation:
The Federal government is a type of government in which sovereign power rests with the central government, while in a confederal government political power rests with individual states and very little with the central government.
