<p> A recent wave of advanced technologies for collecting and interpreting data offer new opportunities for laypeople to contribute to environmental monitoring science. This dissertation examines the conditions in which building knowledge infrastructures and embracing data &ldquo;cultures&rdquo; empowers and disempowers communities to challenge polluting industries. The processes and technologies of data cultures give people new capacities to understand their world, and to formulate powerful scientific arguments. However, data cultures also make many aspects of social life invisible, and elevate quantitative objective analysis over situated, subjective observation. This study finds that data cultures can empower communities when concerned citizens are equal contributors to research partnerships; ones that enable them to advocate for more nuanced data cultures permitting of structural critiques of status-quo environmental governance.</p><p> These arguments are developed through an ethnographic study of participatory watershed monitoring projects that seek to document the impacts of shale gas extraction in Pennsylvania, New York, and West Virginia. Energy companies are drilling for natural gas using highly controversial methods of extraction known as hydraulic fracturing. Growing evidence suggests that nearby watersheds can be impacted by a myriad of extraction related problems including seepage from damaged gas well casing, improper waste disposal, trucking accidents, and the underground migration of hydraulic fracking fluids. In response to these risks, numerous organizations are coordinating and carrying out participatory water monitoring efforts.</p><p> All of these projects embrace data culture in different ways. Each monitoring project has furthermore constructed its own unique infrastructure to support the sharing, aggregation, and analysis of environmental data. Differences in data culture investments and infrastructure building make some projects more effective than others in empowering affected communities. Four key aspects of these infrastructures are consequential to data culture formations and affordances: 1) the development of standardized monitoring protocols, 2) the politics of data collection technologies, 3) the frictions of database management systems, and 4) the power dynamics of organizational partnerships that come together around water monitoring efforts. Lessons from this analysis should inform future efforts to build infrastructures that address problems of environmental pollution in ways that also generate long-term capacity for empowering at-risk communities.</p>