Auckland’s rapid urban growth into greenfield areas presents significant challenges for sustainable stormwater planning, particularly in terms of disrupting natural hydrological systems. This study investigates the potential of catchment-based solutions within Auckland’s strategic planning framework, focusing on two major greenfield development projects as case studies. Through inductive reasoning and thematic analysis, the research identifies key barriers such as unclear policy provisions, overlapping responsibilities, conflicting stakeholder priorities, and inconsistent policy interpretations. These challenges highlight the complexities of aligning urban development goals with catchment-based stormwater management practices. The findings highlight the need for a more integrated planning approach to effectively address these issues and mitigate risks to natural hydrological systems. Additionally, this research offers theoretical insights into the integration of urban planning and stormwater management, providing practical implications for enhancing the sustainability of greenfield developments worldwide. Addressing these challenges is crucial for achieving cohesive and effective catchment-specific stormwater planning that supports both urban growth and environmental sustainability.