The Imperial Valley, which extends across the border of California and Mexico used to be called the Valley of the Dead. It has an annual rainfall of about 2.4 inches, the lowest in the United States. However, it is broad and flat and would be easily irrigable with water from the Colorado, if the Colorado were a tame and clean river, which, at the time, it was most decidedly not. In 1901, a channel was cut from the Colorado to begin irrigation and the Imperial Valley boom was on. This silted up by 1904, so a bypass channel was cut. This silted up too, and so in 1905, the Imperial Valley farmers got permission from Mexico to cut a bypass channel through Mexican territory. And then the Colorado flooded, wiping out the Imperial Valley completely. It did it again in 1906. And again in 1907. Freight cars full of rock and rubble tried desperately and constantly to plug the half-mile wide breach in the Colorado's old bed, but it was not until early 1908, when a drier year was upon the valley, that the Colorado calmed down and allowed itself to be diverted back.
There was only one solution for California farmers dependent on the Colorado - a dam. A dam would prevent the Colorado from flooding the valley and would provide a steady flow of water even in dry years. It would also collect the silt in the river channel itself and prevent the irrigation ditches from silting up. There were only two problems, one physical, one political. The physical problem was that the Colorado was just about the worst river in the world to try to dam. As they had discovered, it flooded at strange and irregular times, jumped its bed constantly, was full of silt, and in general caused all sorts of headaches. The political problem was slightly more acute: California runoff contributes hardly at all to the Colorado. Almost half of the Colorado originates in the Rocky Mountains - if California wanted to ensure that a dam would be useful, they would have to sit down and negotiate with the other Colorado River Basin states, including Arizona, who believed the Colorado was almost a state resource, since nearly half of the actual mileage of the river passed through Arizona.
"Prior appropriation" is a concept in water law that has to do with preventing "waste". If there is no other law or government decision that affects the water rights in a stream flowing across several properties, a person who draws water off of the stream has "appropriated" the water. If he does so for a permissible purpose, such as farming, then the person downstream has no claim against the person upstream for taking water that he had been making no use of. This has the effect of encouraging the development of streams and rivers as quickly as possible. The Supreme Court said that Wyoming, by using the waters of the Colorado River, had established a prior appropriation, and that Colorado could not now claim so much water that would cut off Wyoming's "perfected rights".
Colorado retreated. In fact, it was their delegate, Delph Carpenter, who proposed the division of the the Colorado River Basin at Lee's Ferry into upper and lower basins, splitting the flow between them.
The Compact was negotiated at Bishop's Lodge, a resort just outside Santa Fe, and was actively mediated by the federal government.
Many Arizonans originally supported the Compact, including Carl Hayden, future political mogul of the Central Arizona Project. But Governor W.P. Hunt, one of Arizona's most influential populist politicians and one of the organizers of Arizona statehood, opposed it strenuously, even mentioning it in his fourth inaugural address in 1923. As Arizonans at the time would quip, Jesus may have walked on water, but Governor Hunt ran on the Colorado River. Even Hunt's enemies, like industrialist Lewis Douglas (of the famous Phelps Dodge mining family) quickly took up the banner of opposing or amending the Compact in Arizona's legislature. Heavy-handed tactics by California made matters worse. William Mulholland, Los Angeles' water mogul, who had drained the Owens Valley dry only a few years earlier, announced that L.A. would need 1,500 second-feet of Colorado River water, which touched off even more outrage in Arizona, which was determined not to go the way of Owens Valley, sucked dry to feed Los Angeles' ever-growing need for water.
Explore the Colorado River Compact.
California, meanwhile, became increasingly dedicated to the combination of a dam on the Colorado and the construction of an All-American Canal to serve the Imperial Valley agricultural interests.
In 1925, and then again in 1927, the governors of the Colorado River Basin states met to try to completely ratify the Compact and apportion the waters. The Governors of the upper basin states managed to settle on a distribution for the lower basin of 300,000 acre-feet for Nevada, 3,000,000 acre-feet for Arizona, and 4,200,000 acre-feet for California. This was 400,000 less than California was willing to agree to. Further problems arose when Arizona stated that it felt it was being asked to provide a disproportionate amount of water to satisfy any Mexican claims.
Consider, for example, the Gila, one of the largest tributaries of the Colorado. The Gila is contained entirely in Arizona, and enters the Colorado just above Yuma, only a few miles from the Mexican border. The more water taken out of the Colorado by other states, the more Arizona's rivers must sustain the legal burden that would be taken on by a treaty with Mexico. Since California provides practically no water flowing into the Colorado, Arizona would be at the mercy of the other states.
California, in 1927, finally managed to put together an authorization bill for a dam and canal that stood a good chance of passing Congressional muster. Arizona Senators Carl Hayden and Henry Ashurst launched a filibuster that ended the Boulder Canyon Project Act's chances in the 1927 session, but in the next session, the Senate had enough support to invoke cloture, force a vote, and pass the act.
Explore the Boulder Canyon Project Act.