When your blood alcohol content is 0.08% or higher, you're considered legally impaired in the U.S. While you are certain to be arrested for suspicion of driving under the influence when your BAC is at or over 0.08%, you can still be charged if your BAC is at any level above 0.00%.
Learn more laws about DUI in Denver here https://duilawfirmdenver.com/dui-denver/denver-dui-laws/
More info about limits for Colorado DUI here https://duilawfirmdenver.com/what-are-the-limits-for-a-colorado-dui/