Regional collaboration has become a popular means to manage shared resources and address cross‐jurisdictional boundary issues. The question of who participates in the process, who directly affects decisions, and who benefits from those decisions is critical for understanding the broader value created by regional collaborations. We apply a variety of text mining techniques to meeting minutes to measure how stakeholder participation evolved over nine years of an Integrated Regional Water Management collaboration. We observe that a diverse set of organizations representing differing interests participated to some extent in the process. However, a minority of organizations attended regularly, while most attended sporadically and/or only attended outreach events. Verbs used to describe interaction varied across meeting types, displaying egalitarian patterns of interaction among participants in core leadership meetings and more one‐way interaction among attendees of outreach meetings. We then estimate whether participation affects the likelihood of receiving funding through the IRWM program. Participants who attended the core group meetings most regularly were most likely to receive funding for their projects, suggesting that uneven patterns of participation matter for the substantive value created by the collaboration.