Legal Tools for Blue-Green Infrastructure Planning—Based on the Example of Poznań (Poland)

In Polish law, no mechanisms exist to maximize the application and protection of blue and green infrastructure (BGI) in urban areas. A comprehensive legal framework does not entirely govern urban BGI facilities. Urban planning lacks an appropriate indicator, first and foremost. This study aimed to analyze the Polish legal criteria for the viability of designing and implementing BGI facilities. The authors also researched ways to aid legislators in growing and maintaining BGI in urban areas. In Poznań, a case study was carried out on applying the greenery planning and design law. Local spatial development plans (MPZP) are now the only legal tools in Poland that allow for the protection and establishment of BGI. According to data from Statistics Poland for 2021, the proportion of the country’s total area covered by existing local plans (based on current law) is around 20.51%. When the MPZP does not cover a portion of a municipality, administrative decisions are made by issuing development conditions (WZ) for the plot. WZ may become a tool for environmental damage under investment pressure. Ideas put forward by the authors are: (1) creating urban nature reserves (as one method of land use); (2) evaluating BGI as an integral part of eco-physiographic studies and spatial planning; and (3) creating a new urban indicator with more complex parameters.