The case study is located in the north central Poland, in Kuyavian-Pomeranian province. The catchment area is about 150 km2. Due to highly fertile soils, arable land prevails (nearly 90%) in the catchment. The main crops are cereals, maize, oilseed rape, sugar beet, alfalfa, vegetables and herbal crops. An area covered by catch crops is increasing. Share of irrigated crops is small. The catchment is coping with an increasing water deficit for crop production and high nitrate loads and concentrations in water. These problems are amplified by low precipitation (annual average equals to 500 mm being the lowest in the country, 300 mm in the growing season) and the extensive drainage system (open ditches and subsurface tiles) that drains water excess in wet periods.The OPTAIN project will support the case study team with identifying and developing efficient land management strategies and small technical solutions to improve the soils’ infiltration and water holding capacities as well as its capacity to filter, buffer and transform pollutants.