all over the world the development of rivers has always been part of man's progress is conquest of rivers and his improvement of them for his own use straighted by the rivers of our own west let's consider the four main rivers of the pacific slope to see for ourselves how important they are and how they have been made useful to the people of the western united states in the northwest the columbia river has played a vital role in the development of washington and oregon the sacramento and san joaquin rivers are equally important to the great central valley of california and the colorado river is of dry mendis value to seven states in our southwest starting with the columbia let us look at each of the four others that columbia five miles wide at its mouth is deep enough to carry big ocean vessels upstream for a distance of one hundred miles as much as ten million tons of freight are carried each year by ships on the columbia one of the many products of the pacific northwest is lumber washington oregon the greatest lumber producing states in our country from their great forests some of the timber is carried on the columbia river in the form of log rafts small tugs told the rafts to sawmills on the rivers banks here the logs are cut into lumber and then loaded into freighters for shipment down the columbia and out into the pacific ocean to the parts of the world another valuable product that is carried on the great columbia waterway is wheat wheat that is grown in the columbia river basin the columbia river is also the home of salmon and yields much of the nation's supply of this faith salmon are caught in the river and also in the ocean along the pacific coast about seventy million pounds of salmon are caught each year in the pacific coast states from canneries such as this salmon are shipped down the columbia to many parts of the world center of shipping and commerce on the columbia is the city of portland located on the lam at river a tributary of the columbia one of the new or industries along the columbia is the refining of aluminum such metal industries require a tremendous supply of electricity which is furnished by bonneville dam more than a half million kilowatts of electric energy are produced in bo but dam not only puts the columbia river to work producing power but it improves navigation by deepening the river above the dam and by providing locks which lift the river boats from the lower river through the higher level above the dam water for power here is water for power water that tumbles down five hundred feet with tremendous for us to turn the generators that produce electricity and here is water for irrigation the vast reservoir held by the dam eventually this water will be used to irrigate more than a million acres of land and the spring new world through the pacific northwest irrigation is the principal purpose for which man is developed the sacramento and san joaquin rivers and the great central valley of california the land in the central valley is fertile but it needs water to make it productive to supply this water to great dams were completed in nineteen forty four one of these is just a dam on the headwaters of the sacramento river some of the water held by this dam comes from the slopes of mount justice although its main function is to store water just a dam provides flood control and is a source of electric power for the people of the valley it serves the other dam in the central valley is free on dam on the san joaquin river get supplies water to the southern half of the great central valley from the dam a precious water of the center walking river is carefully distributed through a network of irrigation canals booster stations pump the water to higher canals and control gates regulate the flow into smaller going out until the water finally reaches the fields two million acres of land will eventually benefit from the sacramento and san joaquin river systems not only have these two rivers made the central valley of california region of agricultural well but they are also used for commerce both rivers flow into the bay of scent francisco and goods from that seaport are shipped up the sacramento river to the city of sacramento and up the center joaquin river and through the inland part of stockton and sold two rivers the sacramento and the san joaquin are used by man to increase crops to carry commerce and to develop power in the central valley of california the colorado river is an outstanding example of a river which man has put through his own  from its arson the rocky mountains the colorado flows south through utah and arizona much of this region is dry wasteland and the river at self is normally shallow and of no use for navigation yet man has made this river great about imperial dam on the lower colorado diverts the precious water from the river into a vast irrigation system this dam does not store water but channels it through and carries the water of the colorado river through the desert of southern california through the imperial valley and the court shall of out here the water is carefully directed on to the land the result is colorado does much more farther up the river above them aerial dam is parker dam parker dam was built not for irrigation but to divert water for the city of los angeles from this reservoir behind parker dam million gallons of water a day pass through this pumping station and into the los angeles aqueduct for three hundred miles over mountains and through the desert the water is pump until it reaches los angeles and there is still one more project that man has built to make use of the colorado that project is hoover dam one of the biggest structures ever made by man to put a river to work the great reservoir behind hoover dam is called lake mead the water is used for irrigation and to supply the homes and factories and cities of southern california arizona and nevada the water also produces electric power for more than three million users in the southwest but damage self eliminates the rushing spring floods of the river below hoover dam the colorado river flows evenly throughout the year useful and valuable servant to the people of the great southwest's in addition to its tremendous economic importance the colorado offers beauty and recreation this is the grand canyon of the upper colorado one of the scenic wonders of the world his famous canyon is another asset of the colorado one of the most beautiful and useful rivers of the pacific slo these rivers as we have seen the columbia in the pacific northwest the sacramento and san joaquin and california and the colorado all in the southwest the columbia you remember is why deep river that carries ocean going ships navigation on the columbia is improved by bonneville dam and electric power for the northwest is supplied by grand dam in california both the sacramento and san joaquin rivers are used for shipping but remember that they are more valuable for irrigating the great central valley of california in the southwest it is the colorado which has been brought to work irrigating in southern california and arizona supplying water to los angeles and creating a like trick power for the in our four rivers of the pacific slope we have seen examples of the many ways in which man has put rivers to work for his own benefit the development of the pacific slope is part of the story of man