Natural and manmade factors have drastically changed the character of the river and resulted in the accelerated deposition of sediments all along the entire river valley. The Illinois River delivers about 7 million tons of sedimen annually to the Mississippi River, and about 20.6 million tons of sediment are deposited annually on the Illinois River valley. There are about 53 backwater lakes all along the river, many of which were created by the construction of the locks and dams in the 1930s. Most of these backwater lakes have now lost from 50 percent to 100 percent of their capacities. Some of the other bottomland lakes will also turn into mudflats by the year 2000. Evaluation has shown that the recently deposited sediment is of better quality than that deposited in the middle 1950s or 1960s.