KANSAS CITY, Mo. (AP) — A new study estimates it would cost $18 billion to reroute water from the Missouri River to help irrigate farms in western Kansas, and an additional $1 billion each year to operate the system. The U.S. Army Corps of Engineers estimates that the 360-mile aqueduct would cost $12.2 billion to build over 20 years and $5.8 billion in interest. The Kansas Water Office posted the report online this month. A state committee asked for the study because water levels are declining in the Ogallala Aquifer, which farmers across the region use for irrigation. Experts say current use of the aquifer for agriculture is unsustainable. The proposed channel would start near White Cloud, along the Nebraska border, and end near Utica. A similar 1982 analysis estimated that construction would cost $3.6 billion.