Guelph is the largest Canadian city to rely almost exclusively on groundwater for its municipal water supply. This supply is drawn from 21 active municipal wells and a shallow groundwater collection system distributed across the City and the Arkell Spring Grounds. For more than a century, groundwater has reliably provided safe drinking water to the community. However, increasing population, land use changes, climate variability, and nearby water takings are placing growing pressure on this water resource. Protecting and managing Guelph’s water supply requires a detailed understanding of the regional aquifer system and the factors influencing its resilience now and into the future. The City of Guelph is committed to delivering a safe, consistent supply of drinking water while meeting and exceeding regulatory and quality management requirements. This involves maintaining strong monitoring programs, enforcing source water protection measures, and planning for future demand through its Water Supply Master Plan. At the same time, Guelph works closely with residents, consultants, researchers, and government partners to ensure that groundwater is managed responsibly and sustainably. These collaborations help integrate science, policy, and community priorities into long-term water management strategies. This presentation will highlight how Guelph translates monitoring and modeling into actionable decisions for water allocation, climate-change preparedness, and infrastructure planning. It will showcase lessons learned in managing a groundwater-dependent municipal system under increasing pressures, emphasizing the role of robust data and partnerships in ensuring long-term sustainability.