Subject and purpose of work: This article identifies changes in the economic use of the river valley area of the Krzna, which occurred as a consequence of the regulation of its bed from the Klukówka estuary to the estuary of the Krzna to the Bug. Materials and methods: The analysis was carried out on the basis of cartographic maps and aerial photographs, as well as statistical analyses for the period 1931-2015. Results: The study confirmed the changes in the economic use of the valley of the Krzna River for the agricultural exploitation of the area and increasing crop yields. The biggest changes encompassed wetlands and swamps, mainly in favour of grasslands, whose area increased by 566%, to 2475.7 ha. Conclusions: The regulatory work carried out resulted in an increase in arable land, forests and areas for development, as well as in the reduction of water surface area from 251.94 ha in 1931 to 57.28 ha in 2015.