After the Compact was adopted by the States and Congress, Colorado allowed high-capacity irrigation wells to be developed in the Arkansas River Valley. The well pumping reduced river flow and materially depleted water that would have been available to Kansas. Kansas filed Kansas v. Colorado, No. 105, Original, in 1985 to enforce the terms of the Compact. In 1994, Special Master Littleworth recommended that the U.S. Supreme Court determine that Colorado had violated Article IV-D of the Compact by means of post-Compact well pumping in Colorado. On May 15, 1995, the Court agreed. As a result of the damages and remedies phase, Colorado paid Kansas more than $34 million in damages for Colorado's Compact violations during the period 1950 through 1999. Colorado also paid Kansas more than $1.1 million in costs related to litigating this case before the Supreme Court. This money has been deposited in three funds created by statute that specify generally how and where the money will be spent.
A judgment and decree was jointly developed by Kansas and Colorado based on decisions by the special master and the Court. The decree contains several appendices, such as the hydrologic-institutional model (H-I Model or HIM) and accounting procedures, which are used to determine if Colorado is in compliance with the Compact. This judgment and decree was included in the special master’s fifth and final report which was entered by the Court on March 9, 2009.
An appendix to the judgment and decree was modified in 2009 as a result of an evaluation of the replacement requirements for Colorado well users along the Arkansas River between Pueblo, Colorado, and the Colorado-Kansas state line. The States submitted the modified appendix to the Court in August 4, 2009, bringing an end to the active litigation before the Court.
There have been modifications to the decree appendices over the years. The current decree and appendices can be found on the Supreme Court’s website, https://www.supremecourt.gov/SpecMastRpt/SpecMastRpt.aspx.
Kansas staff and technical experts continue to monitor Colorado's compliance on an annual basis. Each year, the water accounting for the prior calendar year period is reviewed and added to a running ten-year accounting table. Colorado has been in compliance to date.