In intensively farmed areas, headwater streams are often enclosed to increase the efficiency of farming and reduce soil erosion.  Enclosures involve burying open first or second order streams and replacing them with drain tiles installed below the soil surface. We wish to relate the degree of enclosedness of headwater streams in cultivated fields to the downstream ecosystem’s structure and function in the Ausable River basin (ARB) in southwestern Ontario. We first delineated all 2^nd order watersheds in the basin using a Digital Elevation Model and digital stream network and geology, soils, climate, and human activity (e.g., enclosedness, agriculture, transportation, urban) layers to characterize each of the 100s of sub-basins within the ARB.  We then summarized the variability and covariability of the traits of small, 2^nd order sub-basins with multivariate analysis of these natural and human-influenced features, and then selected basins along a gradient of enclosedness for future intensive sampling.  This field sampling will enable us to test the hypothesis that enclosedness affects, among other ecosystem attributes, the diversity and composition of the downstream fish and benthic invertebrate community.