You pose an interesting question. In principle in any rational watershed management and water conservation strategy, riparian habitat is (or should be) protected form grazing. When you look at the Wet Creek watershed on Google Earth ( I have attached a KMZ for the area in which I believe your picture of your post was taken) you get the impression that that is not the case in the Wet Creek area. The areas identified with LS are old land slide areas




The case of the Colorado River Cutthroat Trout Reintroduction is an interesting example. There they used beaver "feeding" with great results to improve habitat.


At the same time close to Wet Creek itself human engineering seems to be copying beaver. Perhaps you can explain what these beaver dam like structures are in the picture below.




Charles Dieter and Thomas McCabe wrote an article in the American Midlands Naturalist in 1989: Factors Influencing Beaver Lodge-site Selection on a Prairie River "Physical and vegetative habitat characteristics were evaluated at 33 beaver (Castor canadensis) lodges during 1986 along the Big Sioux River in eastern South Dakota. Slope of the riverbank was the most important physical factor and horizontal
vegetation cover was the most important vegetative factor influencing lodge-site selection. Beaver preferred the habitat quality of ungrazed areas for lodge sites. Although 60% of the study area was grazed, only six (18%) of 33 beaver lodges were located there."


Also have a look at The Western Watershed Project