Aquatic ecosystems significantly contribute to the attractiveness of any protected area, including NP Paklenica. The Velika Paklenica stream normally sinks in the area beneath Anića luka. It flows in its entire length into the sea during the rainy season in spring, autumn, and winter. This thesis analyzes the impact of rainfall measured at an existing meteorological station Crni vrh in the central part of the NP Paklenica at 1110 m a.s.l. to the length and flow of the Velika Paklenica in the lower part of the stream towards the mouth. Flow was measured daily during April 2021 at two locations, in the most visited and narrowest part of the Velika Paklenica canyon and on the border of NP Paklenica at the entrance reception in the Velika Paklenica canyon. The aim of this paper is to measure and analyze specified values, and the purpose is to determine the relationship between precipitation and water flow length, so that the same can be used in NP Paklenica management, especially in visitor management but also in the aquatic ecosystems management because the water from the middle flow of the Velika Paklenica stream is being used for the partial drinking water supply for Starigrad-Paklenica. Given the relatively poor water resources of the NP Paklenica, a debate on changing this practice is justifiably imposed.