1. Despite wide recognition of the need for catchment-scale management to ensure the integrity of river ecosystems, the science and policy base for joint management of land and water remains poorly understood. We present an interdisciplinary case study of a river basin in southeastern Michigan.

 2. The River Raisin drains an area of 2776 km2, of which some 70% is agricultural land. The upper basin is underlain by till and moraine, and land/use cover is diverse. The lower basin consists of fine textured lake deposits, is of low relief, and land use is overwhelmingly agricultural. Suburban development is pronounced within some regions of the basin.

 3. We suggest that the influence of land use on stream integrity is scale-dependent. Instream habitat structure and organic matter inputs are determined primarily by local conditions such as vegetative cover at a site, whereas nutrient supply, sediment delivery, hydrology and channel characteristics are influenced by regional conditions including landscape features and land use/cover at some distance upstream and lateral to stream sites.

 4. Historically a region of oak-savannah and wetlands, the River Raisin basin was deforested, drained, and converted to farmland during the mid-19th Century. Human population reached a plateau around 1880, and then underwent a second period of growth after 1950, mainly in small urban areas. More recently, the amount of agricultural land has declined whereas forested land has increased, in accord with a general decline in farming activity.

 5. Field sampling established higher sediment concentrations under low flows in areas of greater agriculture. In a comparison of two catchments, sediment loads were up to ten times greater in the more agricultural catchment, in response to similar storm events. A distributed parameter model linked to a GIS showed that an increase in forested land cover would result in dramatic declines in runoff and sediment yield.

 6. Habitat quality and biotic integrity varied widely among individual stream sites in accord with patterns in land use/cover. Extent of agricultural land at the catchment scale was the best single predictor of local stream conditions. Local riparian vegetation was uncorrelated with overall land use and was a weak secondary predictor of habitat quality and biotic integrity.

 7. Investigation of the regulatory agencies involved in land and water management in the basin revealed a complex web of overlapping political jurisdictions. However, most land- use decision-making occurs at the local level of township, city, or village. Unfortunately, local decision-making bodies typically lack the information and jurisdictional authority to influence up- and downstream events.