LANDSCAPE VARIABLES AFFECTING LIVESTOCK IMPACTS ON WATER-QUALITY IN THE HUMID TEMPERATE ZONE

The potential for impact by grazing livestock on unprotected watercour ses may vary with climate, with landscape lever factors including the landform within which the pasture is located, with the biophysical cha racteristics of the watercourse itself, and with pasture and grazing m anagement practices. Policies seeking to implement cost-effective meas ures to protect downstream water quality need to acknowledge large-sca le as well as small-scale processes which can moderate or exacerbate p otential sources of pollution. Applied and scholarly evidence suggest that unrestricted livestock access accounts for a relatively modest sh are of watercourse pollution in humid temperate regions, as compared w ith such watershed-specific factors as leaking septic tanks and confin ement feeding systems. A wide variety of evidence suggests that the de gree of compatibility of grazing livestock with a healthy riparian eco system should be viewed as an hypothesis that is testable on a site-sp ecific basis. Greater understanding of the factors causal to livestock behavior in, and impact on, watercourses may help to better focus pre ventative and remediation efforts by both producers and policymakers.