The paper presents the characteristics of shallow groundwaters of the Polesie National Park – one of five national parks in Poland, where main subjects of protection are water-peatland ecosystems. Its functioning depends on the state of water resources. Data from field mapping at the turn of July and August 2013 used for the analysis show untypically high location of groundwaters in the summer period. Such a situation was caused by abundant atmospheric alimentation that occurred in spring and early summer of the analysed year.