Grass-fed versus irrigated-pasture cattle

There are important climate-related reasons to eat less meat, as well as other environmental reasons for cutting back. My somewhat-defensive, omnivore's response is that grass-fed cattle can be comparable or even superior to plants as a food source since it doesn't necessarily involve changing land from a closer-to-natural state. (Yes, the vast majority of cattle in the US and much of the cattle in other developed countries are grain-fed.)

There's a complication to my argument. Grass-fed cattle could also be grazing in irrigated pasture. Here in Santa Clara County, there are thousands of acres of irrigated pasture. That type of pasture is only somewhat more valuable as habitat than lawns or farms, and water use could be significant (I'm not sure how it compares to typical farm use).

So the ideal beef is from grass-fed, non-irrigated pasture cattle. When can we get the labeling for that?