Water is an irreplaceable and unique natural resource whose quantities are limited and unevenly distributed within space. The importance of water stems from the fact that all life forms and human activities are mostly water related. The Rječina catchment area is a karst watercourse superficially composed of two separate basins: the Rječina basin and the southern part of the Grobničko field, which in hydrogeological terms form one whole, and the main feature of the basin is a large oscillation of water flow during the year. Geologically, the basin is located in the area of Quaternary sediments composed of sand, clay and gravel, and its thickness depends on the amount of sediment deposited in a particular area. Water management includes many segments: environmental protection, drinking water supply, irrigation of agricultural land, protection from harmful effects and many others, and the main goal is to preserve the existing quality and quantity of water for future generations, to disrupt as little as possible water-related ecosystems and aquatic ecosystems, prevent the harmful effects of water that can impair the quality of life of people and infrastructure. Therefore, when developing water management plans, attention should be paid to the climatic, geological and hydrogeological characteristics of the area, the number of inhabitants in the observed area and biodiversity. Such work includes compliance with the applicable regulations, ordinances and laws that serve as guidelines for the adequate conservation of water resources, protection of people and the environment, as well as their use for the purpose of water supply.