Monday’s historic Colorado River agreement represents a big win for California, which only months ago was embroiled in a bitter feud with Arizona, Nevada and four other Western states over how to dramatically reduce their use of water supplies in the shrinking river. The proposition, which came after months of tense negotiations, would see the three states in the Colorado’s lower basin conserve about 3 million acre-feet of water from the river by 2026 — a 14% reduction across the Southwest that amounts to only about half of what could have been imposed by the federal government had the states not come to an accord.