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.
Considering the USEPA average gal/capita/day flow of 40-60 gallons, it does not appear that the current use of 120 gallons per bedroom accounts for peak flow, leakage, or safety factors. Other researchers typically using 40-100 gallons per person per day which, at the upper end, does appear to include a safety margin.