The flooded meadows of the Pamarys region permanently are an object of increased attention and require new solutions using grasslands for farming and sustainable development of the area. During the last decade's new environmental regulations has more tighten restrictions for farming and especially in protected areas. Nemunas delta Regional Park is one of the biggest protected areas in this region. The status of protected area fundamentally changed the farming conditions in polder systems. Summer polders (these are flooded in spring time) are the main chain in the plenty of problems, and proper farming and use of polder systems not only decrease expenses for maintenance, but also essentially improve ecological situation of the ecosystem in such areas. The most important problem still remains fish killing in pumping stations of polder systems. More the 10 years before the Sysa pumping station was modernized installing here screw pumps. It was experimental pumping station for several years ad latter the same pumps were installed in more three pumping stations. Today we have already 14 years experience and can do some conclusions about the use of screw pumps. The history of screw pumps, some practical experiments, analysis of collected data in three different polder systems (with screw pumps and conventional pumps) a comprised in this final Msc. degree work.