Read this excerpt from a speech about hydropower. which pair of sentences contains the hook? in 1881, niagara falls became the location of the nation's first hydroelectric generating facility. it used water to make electricity. the generators that were connected to the falls powered the lights at night for tourists visiting the area. since that time, people have worked at developing hydroelectric power that could replace other energy sources. every state uses hydropower for electricity, but it's definitely an underused energy source. the state of washington gets about two-thirds of its electricity from hydropower. in fact, the grand coulee dam on washington's columbia river is the largest producer of hydroelectric power in the country. washington, idaho, and oregon have some of the lowest energy bills in the country because they rely on water for their energy. can you imagine their savings? the hoover dam is another huge facility that works to store energy. it crosses the colorado river on the border of nevada and arizona. the dam's generators can supply electricity to more than 100,000 households. when operating at full power, the hoover dam can provide power to a city of 750,000 people.