The Black Death was a plague the spread across medieval Europe in 590CE to 1500CE. It was an infection caused by rats and then spread by fleas. The rats were carrying a lot of germs and bacteria at the time so a flea would bite the rat and then would and bite a person.
The average life expectancy of a dam is 50 years, and 25% of the dams in the Army Corps of Engineers National Inventory of Dams are now more than 50 years old.This number is projected to increase to 85% by the year 2020.he Glen Canyon Dam supplies over 5 million people with power (Glen Canyon Dam Adaptive Management Program, 2007). These two dams also have the capacity to store 32,471,000 acre-feet and 27,000,000 acre-feet of water, respectively. In order to harvest hydropower however, dams must be built.
Water is pumped from the pumping station, located just outside of the west dam, through a 2,000-foot (610 m) long, 16-foot (4.9 m) diameter pipe and into the lake via the I/O tower. At peak rate, water flowed into the lake at 1,000 cubic feet (28 m 3) per second. Filling of the lake finished in 2003.