The lack of land use planning and the absence of conservation practices in a watershed can contribute to increased runoff, soil loss, and nutrient transport, which compromise the environmental quality in a watershed, especially the water resources. The objective of this study was to assess the contribution of conservation practices in reducing runoff and soil and nutrient losses using the Soil and Water Assessment Tool (SWAT) in the São Bartolomeu Stream Watershed, which is a significant watershed in Brazil. The modeling allowed us to identify critical areas regarding sediment yield, runoff, and nutrient loss. After that, conservation practices aimed at reducing the impacts of such processes were simulated. We also identified the most sensitive model parameters to simulate changes in management practices. Simulation results showed an average annual runoff (R) of 35 mm, average annual sediment yield (SY) of 51 t ha<Superscript>-1</Superscript> year<Superscript>-1</Superscript>, 3.6 t ha<Superscript>-1</Superscript> year<Superscript>-1</Superscript> of total nitrogen (TN), and 1.6 t ha<Superscript>-1</Superscript> year<Superscript>-1</Superscript> of total phosphorus (TP). When considering the adoption of conservation practices, results showed an increase in water infiltration in the watershed and reductions of 18 %, 66 %, 25 %, and 30 % for R, SY, TN, and TP, respectively. Interventions which prioritize adequate management practices can be highly efficient and avoid changes in consolidated land uses. Copyright Springer Science+Business Media B.V. 2012
