For example, the fields of Western farmers feed the United States and many other parts of the world, and India's irrigation systems have enabled that country to be self-sufficient in food production since 1974. In addition, in many parts of the world dams have helped to remedy life-threatening problems such as poverty from lack of economic development, famine as a result of drought, devastation from floods, and continued disease from lack of potable water supplies.
There are people who wouldn't be alive without dams. 
It said that they have helped to remedy life-threatening problems  which means if they weren't there some people would have died. My statement is correct. 
( z1 person :ARG0-of ( z2 live :polarity - :condition ( z3 dam :polarity - ) ) )