The area is already at 1000ft asl.
The very lowest point in Colorado is about 3300 feet above sea level...the average elevation of the state is about 6800 feet. You
will feel the effects of the altitude. At 5000 feet, the air pressure (and the oxygen partial pressure) is only about 83% that of sea level. At 6000 feet, it's about 80%; and at 7000, 77%.