California's Central Valley is about 400 miles long and 100 miles wide. It is probably the most badly degraded area in the USA. In the 19th century, about 1,000,000 acres of riparian forest existed; 95% was cut down. The rivers are all dammed and contained (temporarily) by levees. Tulare Lake, the biggest lake west of the Mississippi, was drained. The waterbird and salmon populations are only 10% of what they were. Now, it is being paved for housing developments, for long-distance commuters. Still. the bits and pieces that remain intact are quite beautiful. Eventually, the flood control reservoirs will fill up with sediment eroded from the mountains and the inland sea will return.