Mountain and border regions face pronounced challenges in organising efficient plastic waste collection due to complex terrain, dispersed settlement patterns and limited infrastructural capacity. These challenges are particularly critical in transboundary river basins, where mismanaged plastic waste generates cumulative downstream environmental risks. The Upper Tisza Basin, shared by Ukraine and several European Union countries, represents a high-risk area for riverine plastic transport and cross-border pollution. The aim of this study was to assess the efficiency of regional plastic waste collection systems in mountain and border conditions and to identify key factors determining system performance. The research was based on a mixed-method approach combining municipal waste statistics, geospatial accessibility analysis, field observations and qualitative assessment of municipal documentation and publicly available operational reports. System efficiency was evaluated using quantitative indicators including plastic collection rate per capita, container coverage, collection frequency and terrain-adjusted logistical performance. The results revealed substantial spatial disparities in collection efficiency. Lowland municipalities achieved plastic collection rates of 9.8-12.3 kg per inhabitant per year, whereas mountainous municipalities collected only 3.2-5.7 kg per inhabitant per year. In mountainous areas, less than 50% of residents had access to collection points within a 300 m radius, compared to over 80% in lowland settlements. Logistical inefficiency in high-altitude municipalities was more than twice as high due to poor road accessibility and elevation changes. Community-driven initiatives, including decentralised collection hubs and river clean-up programmes, increased local collection efficiency by up to 30% in underserved areas. The findings demonstrated that improving plastic waste collection in mountain and border regions requires integrated solutions combining infrastructural optimisation, terrain-sensitive logistics, institutional coordination and community engagement. The proposed assessment framework could be applied to other transboundary mountain regions to enhance environmental safety and sustainable resource use
plastic waste management; spatial accessibility; border areas; riverine pollution; collection efficiency; river basin management; environmental safety