Without it we could not make a living
要是没有这条河，我们就无法生存下去
......
There is only enough spring water to supply the needs of the house, so we have to pump from the river for farm use
泉水只能满足家庭生活用水，因此我们必须从河里抽水以用于农业生产
......
We have special river birthday parties in the summer
夏天，我们为这条河举办专门的生日宴会

in summer基本上是错的，当然如果你把summer看成不可数名词，应该也行，但是那个应该不是“夏天”的意思。