In the paper, the influence of predicted mine water discharge from the planned excavation of Jurassic limestone from Marylin 1 deposit (Iłża Foothills) on two levels of exploitation (167 and 155 m a.s.l.) on runoff of 5th to 2nd streams order (5th – stream from Śniadków, 4th – Oronka river, 3rd – Szabasówka river, 2nd – Radomka river) was examined. Excavation with its surface catchment creates endorheic area of 32.25 hectares, which will be dewatered. The source material consisted of: topographic and thematic maps, digital elevation model, hydrogeological documentation and field survey results. The analysis included river catchments delimitation, rainfall calculation in the area of the planned excavation mine and its catchment during the average year, month and day with the highest total precipitation during the 10 and 15 minute storms, calculation of specific discharge in gauged and ungauged streams which drains the excavation pit, calculation of the amount of runoff entering the excavation pit and the mine water discharge forming the runoff in subsequent streams. Unreliable rainfall intensity was determined by various methods: Błaszczyk equation, Reinhold formula, Bogdanowicz-Stachy probabilistic model. Specific discharges and runoff of the stream of Śniadków, Oronka river and Szabasówka river were obtained using specific runoff methods, Iszkowski equation and Punzet formula. Runoff of the Radomka river was calculated based on IMGW data (Słowików water gauge). The total percentage of surface water and groundwater at the 155 m a.s.l. exploitation level conditions will reach: 287.0% (year), 297.8% (month) and 467.4% (day) of the average runoff. In the following streams this influence will be moderate: Oronka (up to about 47%), Szabasówka (up to 8%) and Radomka (up to 5%). The biggest hydrological consequences, as a result of surface inflow, will occur after the torrential rain (10-15 minutes) in the stream from Sniadków. The resulting discharge will depend on the time required to pump out water from the excavation mine. In the scenario of the most intensive 15 minutes rainfall (return period 10%), the optimal duration of pumping out the water in the 155 m exploitation level conditions will be about 14 hours. Then, the mine water discharge will not exceed the average year discharge in the stream from Sniadków.