Fill in the words listed below

salt penetrate surface accumulate beneath

irrigation rain serve winter waters

inland store purpose substances lakes

dew reaches an aquifer used

sewage treatment plants

Sources of fresh water

Surface water is water on the 1) _______of the earth, such as in streams, rivers, and 2) _______. It is the chief source of water used for 3) _______. Surface water comes mostly from 4) _______and snow. Rain water flows from land into streams and rivers. Great quantities of snow 5) _______on highlands and mountains during 6) _______. In spring, the snow melts and runs off into surface 7) _______.

In many parts of the world, engineers build dams across rivers to 8) _______water in artificial lakes. These lakes 9) _______as reservoirs that hold water until it is needed for irrigation or some other 10) _______.

Ground water is stored 11) _______the earth's surface in spaces between rocks, grains of sand, and other 12) _______in soil. Water fills these spaces as it moves down through the soil. The water eventually 13) _______a layer of rock or of a soil material that it cannot 14) _______. The ground above this layer becomes a saturated area called 15) _______.

Other sources contribute little to the total amount of water 16) _______for irrigation. In the Negev Desert of Israel, farmers conserve 17) _______and use it to irrigate their fields. In some other areas, farmers use water from 18) _______ to irrigate certain crops. Ocean water can be used for irrigation if the 19) _______is removed. However, the cost of removing the salt and pumping the water 20) _______is extremely high.