Erosion of agricultural croplands is a significant contributor of sedimentation to reservoirs. Here, physiographic and economic models for a large agricultural watershed (2377 square miles with 27 subwatersheds) are integrated for the reduction of sedimentation of one Midwestern reservoir. Sediment reduction and the cost-effectiveness of three agricultural best management practices (no-till, filter strip, and permanent vegetation) implementation were considered under three modeling scenarios: random assignment; the globally most cost-effective approach; and a cost-effective targeting approach. This study demonstrates how physiographic and economic data can be harnessed to yield readily comprehendible cost-effective targeting maps. Cost-effective targeting may be preferable to watershed managers for its “user-friendliness” without too great a sacrifice of the globally most cost-efficient solution.