Hello. My name is Paul Lander with the University of Colorado. As you can see and we know that the West is very arid. In fact, native peoples in the Southwest had a long history of annual migration due to the lack of reliable water supplies for villages and crops. In fact, for early Europeans settling in this area, it became known as the Great American Desert, and you can see in that graphic. Scientists have known for over a 100 years, that west of the 100th meridian, we have a very, very different situation out here, primarily due to the variability in the availability of water both spatially and temporally. However, the prehistoric Hohokam tribe, created one of the largest and most extensive canal networks in the lower southwest. In fact, by about 1200 AD, they had miles and miles of canals measuring 20 meters wide, six meters deep. Some of them miles long and capable of irrigating up to 10,000 acres of crops, very, very substantial public works if you will. What you can see in the map here, is the overlap between the location of the historic canals that the Hohokam belt and those of modern-day canals, which makes sense, you have to follow topography, you want to use gravity, getting water to where it goes but also reinforces the idea that water is important to this area no matter what culture is trying to establish itself in this area. One of the first explorers in the southwest region was John Wesley Powell. He explored the region at the behest of Congress and wrote the report about the arid lands and one of the things he discovered is, it's very, very different out here. There's not a lot of water and it's distributed quite differently as we said both spatially and temporally. So there's a fair amount of water in certain accentuated places but not a lot in other places. Powell notices that it's quite dry out here, left a really dry barren landscape. We might want to think of the management of water is incredibly important to the point where he suggested to Congress and illustrated in this map, that states which were at this point not yet defined, actually define themselves by watershed boundaries. Water is that important to this region of the West. It became clear that water was going to be important for the kinds of activities that settlers wanted to do as they move into this area, primarily mining and agriculture that we know in the 19th century. You can see photos of this and lots of historic records, mining particularly and that's where the water system and the West you'll hear more about got its origins with the idea of staking a claim for water. So I had some security to settle the land. We often forget now in the 20th century, where growth is a big issue for us, that one of the driving forces in the 19th century, is could we get people to move out here and stay on the land? That was really, really important. Some cultures did that better than others because of their organization. Most notably the Mormons in Utah. You can see a ditch here that Mormons literally hand dug out of rock. In fact, by the late 1800s, Mormons had dug over 1,000 miles of canals across all of Utah, being able to irrigate thousands of acres and increasing the productivity of their farmland tremendously. There was a real need for holding back water, building dams and diversions, which is a fundamental concept we would know from almost any arid, semi arid climate, where water beings most of the activities we wanted to do were dependent on water. You need storage up some volume and some accessibility. So we needed to have these waterworks to be able to settle the West and it was really important, and build we did. You can see from the graphic here, we put in a lot of dams in the West, don't get too scared here, most of these are in relatively small scale, but nonetheless, it became very, very important to the settlement of the Western United States, as in other word arid regions, to be able to have water available, and the best way we knew how to do that is to actually building storage. As impressive of those waterworks were that the Mormons did and other settlers to the early Western United States, they weren't of a scale that was really going to get us to that next level to have large bodies of people moving to the West and feeling secure in their opportunities to build economies. That really necessitated the passage of the Reclamation Act in 1902, and the US government stepping in as a player to bring that level of development to scale if you will. You can see in this graphic here, the thousands of acres that by the early 20th century, were already under construction or planned to bring water to irrigating thousands and thousands of acres. So a major transformation of that American desert if you will. One of the reasons for it is we realized early on and it's happened in most Western states, this pension to want to live where we want to live regardless of where the water is. This illustration, a cadre of California, most of the water naturally occurs in the North, most of the people and most of the farming are in the South. So that necessitated delivery and a building of a huge Infrastructure. In my home state of Colorado, we call it the 80-20 state, 80 percent of the waters are in the Western slope, but 80 percent of the people are on the Eastern slope. There's always this division. You can also see in this graphic all the little arrows along the continental divide, that's to remind us over the last 150 years, we've built three dozen or more major diversions, bringing water from that letter region to the drier region where most of the population is. So little things like mountains have not gotten in the way of settling the American West. Well, most of the large infrastructure that we've seen was built primarily for hydro power irrigation and flood control in the western United States. The availability of those large pockets of water was a boon to the Western United States particularly in the development of post-World War II, as cities began to track more and more of the population to move to a better climate having economic opportunities. You can see in the graphic here, just three area we've identified, Los Angeles, Denver, and Phoenix, that grew substantially during the 20th century, primarily because of the availability of those relatively cheap, high reliability water supplies, cities are also going to grow substantially in the future. Increasingly, they have the political clout to think about promoting and changing the way we manage water in the Western United States.
