The treated wastewater discharged from the Subotica wastewater treatment plant (WWTP) constitutes approx. 2/3 of the inflow to Lake Ludas, the rest is surface and groundwater inflow from the nearby area. The lake volume is about 10 Million m³ and water exchange takes about 7-8 months. Therefore, the quality of the WWTP effluent is of utmost importance for the water conditions in Lake Ludas. The Tisa-Palic Channel was completed in 1995 with the purpose of pumping water from the Tisa River to Lake Palic – which turned out to be uneconomic and is therefore not in use.
The Palic-Ludas Channel constitutes the outflow of Lake Palic and the main inflow to Lake Ludas. Obviously, the water quality of Palic influences that of Ludas. Lake Ludas discharges into the Kereš River which is a tributary to the Tisza River which in turn discharges into the Danube.