The study of water as a K-12 science idea often divorces its properties from its deeply politicized history as a resource that has been limited, compromised, and intentionally withheld from nondominant communities. Although a robust body of scholarship has aptly critiqued decontextualized and depoliticized pedagogies and called for critical science-learning environments designed through the lens of equity, historicity, and power, more insight is needed into how children develop in relation to these design imperatives and within sociopolitical contexts where environmental issues pose a direct threat. We report select findings from a 2-year ethnographic project that investigated Black student agency in a school with a place-based design. Specifically, we hone in on the themes of water and water justice, which inspired the development of a socio-scientific unit enacted in two 4th-/5th-grade classrooms. This unit coincided with the initial spike in public awareness around the still unresolved water crisis in Flint, MI. For this article, we situate the "Flint" module as an illustrative case of justice-centered science pedagogy and analyze Black students' disciplinary, affective, and sociopolitical understandings. We found that children's meaning-making shifted from individualized accounts to critical, systemic explanations of environmental justice issues. The saliency of children's affective understandings throughout the unit was also captured. We expound on these findings and conclude with a discussion of implications, particularly as it relates to the ethics and politics of developing critical scientific capacity in young children to confront lived environmental human rights issues.