be divided into 2 type is surface water in lakes and surface water in rivers. Lake are important source of accessible freshwater. Freshwater supply in lakes can come from different sources , in instead of just one source. Next ,surface water in rivers are another source of freshwater. Rain and snow fall in the mountains, and some of the water goes into the ground. However , some of the water stays on surface and flows downhill. Many people worry that the demand for water could grow higher than the supply. One way to solve the problem may be to find ways to use saltwater. In 2012, a company in California began an experiment to change saltwater from the ocean into freshwater.