Domestic livestock grazing detrimentally affects water quality and quantity (cattle consume 20 gallons of water daily). 1
In 1988 the General Accounting Office concluded that poorly managed livestock grazing is the major cause of degraded riparian habitat on federal rangelands. 2
In the arid West, livestock congregate in fragile riparian zones where they mow down vegetation and trample streambanks, which shrinks the channel, reduces streambank stability, and increases water temperature, velocity and turbidity. Deep, narrow, meandering cold-water streams enclosed in lush vegetation become bald, wide, shallow, rocky drainages that are vulnerable to flood events.
The best review of the impacts of livestock grazing on riparian resources was authored by Belsky, et al., 1999. Survey of livestock influences on stream and riparian ecosystems in the western United States. J. Soil and Water Cons. 54:419-431. Available in PDF format from the Oregon Natural Desert Association at http://www.onda.org/library/papers/index.html.
1. See Forest Guardians. "Endangered Streamside Forests" (factsheet) (PDF).
2. GAO. 1988. Public rangelands: some riparian areas restored but widespread improvement will be slow. RCED-88-105. General Accounting Office. Washington, DC: 11