Introduction
Livestock producers are legally responsible to prevent the pollution of surface waters that grazing livestock can cause due to the waste products they generate. Some of the major non-regulatory reasons for adopting good livestock management practices are improved and/or increased animal health, pasture productivity, wildlife habitat, land value, and ecosystem health.
Individuals and organizations concerned about the effects of livestock grazing on the environment tend to view grazing as a static process with fixed negative effects on an ecosystem, regardless of differences in management. Dr. Nathan Sayre, professor of human geography at the University of California, Berkeley, uses ranching to make a point about sustainable natural resource use in the western United States:
[Ranching] has outlasted beaver trapping and bison hunting. Beaver and bison look like cases where an activity was ecologically unsustainable. But in truth it wasn’t the activities per se that were unsustainable but the way they were practiced in the 19th century, which can be traced to economic forces and property relations rather than ecology... The way [ranching] is practiced today is radically different from the way it was practiced then, even if we call it by the same name. (2005: 2; emphasis added)
Applying this dynamic perspective of historical land use to water quality, the presence or absence of cows in a riparian area is not as important as the way they are managed. Also critical are the effects of plant community changes from influences such as climate, weather events, and fire on potential pollutants such as sediment, pathogens, nutrients, and stream temperature.
This bulletin addresses the effects of livestock grazing on water quality in streams and demonstrates the relationship that commonly associated pollutants have on ecosystem health. Sediment, pathogens, and water temperature are emphasized to illustrate how livestock management practices that promote healthy pastures1, rangelands2, and forestlands are steps toward ecosystem health.
According to the National Research Council (1994: 35), rangeland health deals with the “degree of integrity of the soil and ecological processes that are most important in sustaining the capacity of rangelands to satisfy values and produce commodities.” For purposes of this discussion, ecosystem health carries the same definition as rangeland health. Because clean water is commonly valued as one of the most important “commodities” natural ecosystems provide, federal and state laws dictate that a standard level of water quality be maintained. A decline in water quality (regardless of cause) is therefore often considered a result of “malfunctioning” ecological processes necessary for capturing, storing, and safely releasing clean water. When referring to rangeland health within a specific geographic area (that which drains to a common water body), the term “watershed health” is often used.