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Montane meadows and wetlands of the world's arid regions are—when properly functioning--flow regulating, water storing features that may extend streamflows where rain, snowmelt and/or springs are insufficient to support a year-long surface-water presence. However, water storage and flow regulation along gradients are severely compromised by the formation of induced hummock and hollow patterns that, by creating open channels, increase flow rates through affected wetlands. The formation of induced wetland hummocks was attributed by Icelandic researchers to overgrazing by horses and by Johnson to overgrazing by cattle in Colorado mountain fens. We tested for a domestic livestock effect by comparing surface roughness using six fence-line contrasts at four meadow and wetland complexes within the upper Sweetwater River watershed of Fremont County, Wyoming, US. We computed a surface roughness index (SRI) as the standard deviation of micro-topographic measurements made using an erosion bridge. The erosion-bridge measurements were made along transects located 20 m inside, or outside, of fence lines. The inside comparison at each of the fence lines was either not grazed or grazing was very limited so that wet-soil trampling by domestic livestock was light or absent for 18+ years (hereafter, “ungrazed”). The average SRIs for the ungrazed wetlands was 42. It was 82, or about twice the surface roughness, for the grazed side of those fence lines (p=0.028, n=6). The site with the longest period of conservation management (50+ years) had an inside SRI of 21, compared to 108 outside. We suspect macrotopography, hydrology, and mineral-soil are factors in induced hummock and hollow patterns but we conclude that our evidence supports the thesis that induced hummock and hollow patterns result primarily from grazing damage by domestic livestock. We recommend meadow and wetland communities be protected from domestic livestock grazing while soils are wet.