Land management at the major watershed—agroecoregion intersection

ABSTRACT:

The watershed natural resources management framework is prevalent today because land use in watersheds is presumed to be reflected in receiving stream water quality. However, landscape characteristics affecting soil erosion and water quality (eg., precipitation, geomorphology, slope, soil internal drainage, cropping system) often vary significantly within a single large watershed (> 200,000 ha). A uniform watershed best management practice would not account for this variability and would not be satisfactory for soil conservation, water quality, or socioeconomic returns. It is highly unlikely that stream water quality monitoring will take place on enough small streams within a large watershed to capture the landscape variation. We have developed “agroecore-gions” to quantify this variation, based on empirical data from the Minnesota River Basin (MRB). This approach is needed to help target cleanup efforts to the most sensitive soils and landscapes within the most critical watersheds. Our work shows that soil eradibility index variability and stream biotic habitat scores were better represented by agroecoregions than by watershed. Stakeholder characterization and economic analysis reveal a large variance in attitudes and beliefs about pollution issues and mitigation costs in the MRB, due in part to problems of scale perception (e.g., entire basin, major watershed county, city, farm). We suggest that watershed management in highly agricultural watershed will be most effective when hydrologic watersheds are used as a framework that is complemented by agroecoregions to identify, and target regions where specific combinations of best management practices for agricultural sediment and phosphorus abatement are most appropriate.