The Transcarpatic Basin which includes the Maramureş Basin (and within it the PHCTS area) is the largest intra-Carpathian lowland area, structured on a substrate with different geology, consisting in igneous rocks and crystalline schists, in the high areas and sandstones, conglomerates, marl, clay and sands in the central lower part. These features along with important rainfall amounts (up to 1800 mm in Ukrainian side) create conditions for a surplus in water resources budget, along with extreme hydrological events which are becoming very common. The average discharge values in PCHTS area go up to 40 l/s.km2 in high mountain area, while in the lowland space the values are around to 5 l/s.km2. Although, the surface water resource is plentiful its capitalization is facing serious problems due to pollution of various origins, from the one related to former mining activities, to those linked to the existence of human habitats which provides different residues. As for the underground water resource, the relatively impermeable substrate creates poor conditions for reserves accumulation and gives unfavorable chemical properties for accumulated water. Overall, water balance is in surplus with rainfall values nearly double compared to the drainage ones and aridity index values which barely exceed 0.5.