Today, the Central Valley is one of the most productive growing regions of the United States. But to enable this, water control was needed to prevent rivers from overflowing during the spring snowmelt while drying up in the summer and autumn. As a result, many large dams, including Shasta Dam, Oroville Dam, Folsom Dam, New Melones Dam, Don Pedro Dam, Friant Dam, Pine Flat Dam and Isabella Dam, were constructed on rivers entering the Central Valley, many part of the Central Valley Project. These dams have had a profound impact on the physical, economic, cultural, and ecological state of Central Valley: for example, enabling development of its vast agricultural resources but leading to the loss of the Chinook salmon.