Łódź is the third-largest city in Poland, located in the central part of the country. It currently has a population of 753,192, although this number has been steadily declining in recent decades. Łódź serves as the capital of the Łódź Voivodeship. While it was granted city rights in 1423, the city experienced its most dynamic growth in the 19th century, when it became a major center of the textile industry in Central and Eastern Europe. Since 2004, the City of Łódź has functioned as an LTSER platform within the LTER network and a demonstration site for the UNESCO Ecohydrology Programme. It offers a wide range of transdisciplinary research opportunities—spanning from ecosystem engineering and biotechnology to socio-ecohydrology, ecology, and the life sciences. From 2005 onward, successive European projects have enhanced the city’s approach to integrating biota–hydrology interactions into urban planning and water management. Key initiatives include: 2005–2010 – SWITCH Project: Established the foundations for developing sequential sedimentation–biofiltration systems on Łódź’s rivers, with the first system constructed on the Sokołówka River. The project also enabled the construction and testing of a cascade of urban reservoirs for mitigating PCB pollution and regulating water flow. These included the Wasiak Dry Reservoir, Wycieczkowa Dry Reservoir, Teresa Reservoir, Żabieniec Reservoir, and Zgierska Reservoir. 2010–2015 – LIFE EHREK Project: Facilitated the transfer of knowledge from the Sokołówka River to the Bzura Valley, where cascade reservoirs were equipped with biogeochemical barriers to improve water quality in bathing areas and prevent cyanobacterial blooms. 2014–2022 – Łódka River Project: Focused on constructing a dry reservoir and sedimentation zone to improve local water retention and quality. 2019–2023 – WaterWorks2017 ATENAS Project: Supported the creation of a series of rainwater retention basins in city courtyards and the development of a rainwater-retaining façade garden and recreation area at the Faculty of Biology, University of Łódź. 2023 – Sokołówka River Extension: In collaboration with the City of Łódź and Ecol-Unicom ERCE, a hydrophyte water treatment plant was added to enhance the retention and purification of stormwater from nearby residential areas. 2020–2025 – H2020 EuPOLIS Project: Supports the transformation of an urban passage into a climate-regulating green corridor, promoting urban resilience and ecosystem services. 2024–2026 – Interreg Central Europe “Re-public Spaces” Project: Focuses on the revitalization of public spaces in historic districts, including the adaptation of a city courtyard into an exemplary rainwater-harvesting infrastructure that merges architecture with ecological function. 2025–2027 – Lamus River Restoration Project: Involves the reopening of the river channel and reconstruction of in-bed habitats to enhance biodiversity, aesthetic value, and recreational potential in Kilińskiego Park. The project also includes increasing plant diversity and providing complementary recreational infrastructure.