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TCL > March 2005 Issue > Wyoming v. Colorado: A “Watershed” Decision

March 2005       Vol. 34, No. 3       Page  37
Historical Perspectives

Wyoming v. Colorado: A “Watershed” Decision
by Frank Gibbard

This historical perspective was written by Frank Gibbard, a staff attorney with the Tenth Circuit Court of Appeals and Secretary of the Tenth Circuit Historical Society. The views expressed herein are those of Mr. Gibbard and not of the Tenth Circuit or its judges. He may be reached at

Aside from sports rivalries, Coloradans tend to get along pretty well with their neighbors to the north. There is one area, however, that has divided them over the years: water rights. Both Colorado and Wyoming are west of the 100th meridian, making them part of the "arid west." Both states have always relied heavily on river water to supply their cities, industries, and agriculture. Early on, both states adopted the doctrine of prior appropriation, which gives priority to earlier diversions from the same stream for beneficial use over those made later in time. [See, e.g., Coffin v. Left Hand Ditch Co., 6 Colo. 443, 446 (1882); Willey v. Decker, 73 P. 210, 215 (Wyo. 1903).]

Of course, rivers do not respect state boundaries. An interesting issue arose once water users became big and powerful enough to conduct major diversions from interstate rivers. If prior appropriation governs reciprocal rights of users within a state, what happens when a river or stream begins in one state and then flows, downstream, into another? Can the users in an upstream state, like Colorado, take all the water, leaving none for the downstream state? No, said the U.S. Supreme Court in Kansas v. Colorado [206 U.S. 46, 100-18 (1907)]. The decision in that case laid the groundwork for the decision in Wyoming v. Colorado [259 U.S. 419 (1922)], another major western water law case.

Although the principal parties in Wyoming v. Colorado were the two named states, the actions that precipitated the lawsuit were those of the Larimer County Ditch Company of Colorado. Larimer Ditch set its eyes on the Laramie River, which begins high in the Rocky Mountains in Colorado, then flows down into Wyoming before joining the Platte. (The Laramie River actually flows north, heading downstream and downhill into Wyoming from its headwaters in the mountains in Roosevelt National Forest in Colorado, before turning to the west in the state of Wyoming. Then it continues downstream where it joins the Platte River.) Larimer Ditch had plans to drill a tunnel under the Never-Summer Range, and to divert water from the Laramie River into another watershed.

Wyoming, a heavy downstream user of the Laramie River, balked at this proposal. It filed suit on the U.S. Supreme Court’s original docket in 1911, but the case was not decided until eleven years later, in 1922. Justice Willis Van Devanter, the only justice from Wyoming ever to sit on the U.S. Supreme Court, wrote the opinion for the Court.

Wyoming’s argument was this: The prior appropriation doctrine contemplated that when a farmer took water from a river to irrigate his or her fields, the runoff would find its way back downstream, benefiting users farther down the river. The plan Larimer Ditch proposed, however, would take the water it diverted out of the watershed altogether. The state of Wyoming argued that this sort of diversion violated the prior appropriation doctrine. The U.S. Supreme Court disagreed, noting that "[d]iversions from one watershed to another are commonly made in both states and the practice is recognized by the decisions of their courts." [Id. at 466.] The Court then engaged in a complex equitable apportionment of Laramie River water between users in Colorado and Wyoming.

The practical effect of this decision was huge, because it helped force downstream states as far away as California to hammer out the Colorado River Basin Compact, which in turn resulted in the construction of Lake Mead and the Hoover Dam. As for Colorado and Wyoming, the decision in Wyoming v. Colorado unfortunately did not result in permanent peace and harmony. They were back in court on Laramie River issues in 1932, 1936, and 1940, before a modified decree was entered in 1957, leading to a few decades of peace.

It was not yet time, however, to close the water law division in the Colorado and Wyoming state Attorneys General offices. In fact, Wyoming v. Colorado was not the only case involving the allocation of the Platte River that would make its way to the U.S. Supreme Court. In the 1980s, Nebraska sued both Colorado and Wyoming over alleged violations of another apportionment decree, dating back to 1945, involving the North Platte River. That litigation continued until 2001, when the states and other parties involved finally settled it. [See Nebraska v. Wyoming & Colorado, 534 U.S. 40 (2001) (decree approving final settlement stipulation).]

For this case, the Court had wisely appointed a special master to do the heavy lifting, an assignment for which he received the Court’s thanks and the sum of more than $2 million for fees and costs, paid by the parties. Nebraska v. Wyoming appears to have settled matters on the North Platte for the time being. Nevertheless, an honest observer of Western water law issues might have grounds to believe that this will not be the last interstate case fought on the issues of equitable apportionment.


Congress included a provision recognizing the beneficial use/prior appropriation principle in the 1877 Desert Land Act [19 Stat. 377, codified as amended at 43 U.S.C. §§ 321-23], perhaps recognizing that 640 acres does not do anyone much good in this part of the country unless there are water rights to go with it. Originally published in 1948, David Lavender's book, The Big Divide: The Lively Story of the People of the Southern Rocky Mountains from Yellowstone to Santa Fe 260-65 [Edison, NJ: Castle Books, 2001), contains a colorful discussion of the circumstances surrounding the dispute in Wyoming v. Colorado. Also of general interest on the history of Western water issues is Reisner, Cadillac Desert: The American West and Its Disappearing Water, rev. ed. (New York, NY: Penguin Books, 1993). 

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