Precipitation ranges from 18 inches per year along the Sacramento River to 90 inches in the mountains. Water resources are essential to our existence in many different ways. We consume water directly. Water is required for the growth of food crops, livestock, forests, fish and wildlife. We use water for cooking, sanitation, fire protection and manufacturing.
Water resources create recreational and scenic opportunities.
To reach surface water bodies precipitation must fall on the land and move downward in rivers and streams. The quantity, quality and rate of flow of water from the land is largely determined by vegetation, soil characteristics and surface slopes. Man also has a great influence through his control of land uses and vegetation. The management of watersheds is an important as the control of surface waters to the preservation of water resources. Man's activities often upset the ecological balances of good watersheds.