<p>The Chesapeake Bay Watershed has faced long-standing challenges to water quality, a condition that impacts its residents access to clean air, water, and economic status. We suggest that collective action is necessary by watershed residents to address this problem. But, before collective action may be encouraged, we must first reliably measure the four stages of collective identity. Here, we briefly review the theoretical foundations for constructing tools that measure the first two stages: knowledge of the group and knowledge of group membership, or in the case of a watershed, general and local knowledge. Results from a survey of Pennsylvania residents show that measuring such knowledge is possible and that there are key differences between general and local knowledge. We discuss practical applications for watershed managers and describe options for shortening the indices.</p>