In the planning of irrigation discharge provision, an important factor to note is the amount of discharge data expected to be avaible for irrigation area in Kedunglimus Arca . This study aimed to figure out the mainstay discharge in Pelus River for irrigation discharge planning in Kedunglimus Arca. The results were expected to be information materials that could be used for irrigation planning. This research was conducted through the collection of data obtained from the Depaterment of Public Works,Water Resources Management Center of Serayu Citanduy Purwokerto and Depaterment of Water Resourse and Highways of purwokerto.the data included the rainfall data, and then analyzed by using Thiessen method. Analysis on mainstay discharge of Pelus River was conducted by using Mock method.The results on mainstay discharge of Pelus River by using Mock method for irrigation discharge planning in Kedunglimus Arca based on cropping system in 2015 amounted to 0.066 m³/s.