Barmyardgrass is an annual grass that would be germinating from seed about now, so it would be very small, not yet prominently visible in your lawn.  By midsummer, it will show its typical flattened stem, often reddish at or near ground line (photo).  It has very distinctive seedheads.  It is also known as water grass because it thrives in moist soils that may not drain well.

So, if you are seeing a well-established, large grass that is now green and actively growing, it's not barnyardgrass.   If I had to guess, it would be that you have some clumps of tall fescue (a perennial grass) in your lawn.

Barnyardgrass is best eliminated by keeping it from maturing seedheads. 

Pre-emergent herbicide ("crabgrass preventer") applied in late March will keep barnyardgrass from appearing in your lawn.

Another weedy grass possibility is that you may have quackgrass, an invasive, fast-growing Noxious Weed in CO.

Quackgrass spreads quickly from underground rhizomes.  It appears early and greens up quickly, before the desirable Kentucky bluegrass of your lawn does.

Right now it would appear taller and wider-bladed than the Kentucky bluegrass it is growing in.  It has a blue-green-greyish color