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.
Answer:
between 200 and 269 feet (60 and 82 metres) in height.
Explanation:
Answer:
1km
Explanation:
A scale of 1:25,000 means that 1 meter on the map equals 25,000 meters on the ground.
So,
Converting 4cm to meter;
4cm/100 = 0.04m
If;
1m = 25,000m
0.04m = ?
25,000 * 0.04 = 1000m
A) because igneous rock will take a lot longer to erode compared to sediment.
