Efforts to value particular dimensions of environmental quality may misrepresent true social values if dimensions of environmental quality interact and researchers nonetheless seek to value single dimensions in isolation. While prior work illustrates that substitution among environmental improvements may occur, questions remain regarding the practical implications of such interactions for microlevel policy evaluation and whether similar effects occur when policies unavoidably include improvements in some resources and degradations in others. This paper identifies potential effects of preference interactions among watershed management components, with an emphasis on whether resource interactions can create substantial shifts in willingness to pay for policy changes.