Water-sensitive urban design (WSUD) is a subset of nature-based solutions (NbSs) that are implemented worldwide. However, the WSUD guidelines in some local contexts, such as Southeast Asia, remain unclear both for ecological and cultural reasons. This study aims to gather collaborations between researchers, designers, and laypeople in WSUD, which have the potential to be implemented to address water quality issues. The study consisted of three stages: site selection, a design workshop, and public interviews. Utilizing geo-design principles and geographical data, the potential pilot site was identified: a vacant space next to the Tha Phae Gate Plaza. A two-day workshop with landscape design experts yielded six conceptual designs, focusing on diverse themes such as water treatment, plant-based solutions, educational opportunities, and cultural enrichment. Public interviews provided insights into the community’s perspectives on stormwater management, desired amenities, environmental considerations, and governance concerns. The results highlighted a collective interest in using NbSs for stormwater treatment and enhancing the area’s recreational and educational potential. This study offers a comprehensive approach to addressing water quality issues in urban settings while considering local cultural, recreational, and environmental needs.