California’s interconnected water system serves over 30 million people and irrigates a lot of farmland. As the world’s largest, most productive, and most controversial water system because California is the states which is the richest states and the most populated states in the USA, it manages over 49 km3 of water per year. Our text will be speak about four things which is the geographic situation of the California, the reason of the requirement of water , the building like barrage realized for take care of water and the war about water.

The states of California is a states of south-eastern of U.S.A, next to Oregon (North), Nevada and Arizona (west) and Mexico (South). In the eastern, there is the Pacific ocean. California is mountain area. Effectively, there are a lot of mountains in California: The Sierra Nevada in eastern, Mojave Desert in southern, Coas ranges and Peninsular ranges in western and Klamath Mountains in Northern. At the center of the state, is The Great Valley. Next to the Ocean, there are some valleys between the mountains.
Generally, we can say that California has a particular Mediterranean climate ( because the summer is cool and foggy.) but there are 3 big climate in California. First, on the coast of the Pacific Ocean, it is a temperate climate like France. But there is a mountain climate on Sierra Nevada. And the last, an arid climate on the Mojave Desert.
In California, there are not a lot of precipitations: in north-western and Sierra Nevada, there are medium precipitations. In the Great Valley, the center of the states, the south-western and the Pacific coasts, there are less precipitations. And finally in the Southern of the state, there are very very less precipitations like in the Death Valley where there are less 50mm of precipitations.

Several principal lakes are presents in California: Clear Lake, Mono Lake, Lake Honey, Lac taoe( a very big artificial lake 502km2) and Salton sea (the biggest artificial lake of