You realize there are laws in Colorado that prevent people from using, daming or stopping the flow the rain water. It must, by law, flow down the rivers and into Kansas where it is used for irrigation.
Most of this water is going to Nebraska, not Kansas.
Kansas has been suing Colorado for more than 100 years : often over the Arkansas River.
Much of this flood water will end up in the South Platte River : It flows directly past the communities of Brighton and Fort Lupton, and is joined in succession by Saint Vrain Creek, the Little Thompson River, the Big Thompson River, and the Cache la Poudre River, which it receives just east of Greeley.
East of Greeley it turns eastward, flowing across the Colorado Eastern Plains, past Fort Morgan and Brush, where it turns northeastward. It continues past Sterling, and runs into Nebraska between Julesburg, Colorado and Big Springs, Nebraska. In Nebraska, it passes south of Ogallala and joins the North Platte River near the city of North Platte.
http://www.crh.noaa.gov/mbrfc/