By SUMAN NAISHADHAM WASHINGTON (AP) — U.S. officials on Monday are expected to declare the first-ever water shortage from a river that serves 40 million people in the West, triggering cuts to some Arizona farmers next year amid a gripping drought. Water levels at the largest reservoir on the Colorado River — Lake Mead — have fallen to record lows. Along its perimeter, a white “bathtub ring” of minerals