Residents of Košice, Slovakia were surveyed about their willingness to pay for improving a polluted urban lake. On average, people were willing to pay 11 EUR per year for better water quality. Factors like income, use frequency, and knowledge influenced how much people were willing to pay. Having children in the household increased willingness to pay, while knowing about city cleaning efforts decreased it. The distance from the lake also affected willingness to pay, with closer residents being more willing to pay for improvements.