Best management practices (BMPs) are widely accepted to control both point and nonpoint source pollution. However, the placement and selection of BMPs plays a vital role in pollution reduction. Therefore, the objectives of this study were (1) to identify pollution generating areas priority areas (high, medium, and low) using four different targeting methods: concentration impact index (CII), load impact index (LII), load per subbasin area index (LPSAI), and load per unit area index (LPUAI), (2) to apply BMPs in the identified priority area to evaluate effectiveness, (3) to assess the spatiotemporal variability of critical source areas (CSAs), and (4) to identify the best BMP and implementation site considering social, economic, and environmental issues using different spatial targeting methods. Ten BMPs were implemented in the identified priority areas in the Saginaw River Watershed by the four targeting methods using the Soil and Water Assessment Tool (SWAT). Analytical hierarchy process (AHP) was used to compare influential criteria with different weights during the BMP selection process. Results suggest that the LPSAI is the best method for sediment targeting whereas the CII is the best method for total nitrogen (TN) and total phosphorus (TP) targeting. Terraces and native grass were the most effective BMPs whereas conservation tillage and no-till were the least effective BMPs both at subbasin and watershed level analysis. In regard to the spatiotemporal variability in the CSAs, a distinct change in high priority areas ranking was observed due to native grass implementation by the end of second year whereas a minimal change in high priority areas was found in case of contour farming due to the greater pollution reduction capacity of native grass compared to contour farming. Based on environmental, economic, and social issues, strip cropping was preferred in all CSAs based on the subbasin level analysis while strip cropping and residue management were preferred in the CSAs for the watershed outlet analysis.
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