The extreme inflow (annual maximum discharge (AMD)) are used for design of dams, bridges, culverts and flood control structures. The analysis of extreme inflow plays an important role in understanding the flow behaviour even after the construction of the large reservoir. The non-parametric trend analysis techniques (Modified Mann–Kendall test and Innovative Trend Analysis) and parametric distribution fitting provide insights into the data set. In this study, trend analysis of annual maximum discharge into the large reservoir was carried out using Modified Mann–Kendall (MMK) test and Innovative Trend Analysis (ITA). Further, the distribution fitting was also carried out to the AMD into the large reservoir using generalized extreme value type I distribution. The total 84 years data of annual extreme inflow at Ukai dam, India were divided into Pre-dam (1939–1972) and Post-dam (1973–2022) scenarios. The MMK test results indicated no trend in the Pre- and Post-dam scenario at 5% significance level. However, the result of ITA indicated an increasing trend in the Pre dam scenario and no trend in the Post-dam scenario for the AMD. The 100 year return period AMD is computed to be 46,411.17 m3/s and 34,147 m3/s for the Pre- and Post-dam scenario respectively. The comparison of the Pre- and Post- dam scenario of AMD indicated that the spillway gates of the Ukai dam are sufficient to discharge the flood corresponding the 730 year return period into the Ukai dam. The study presented in this paper can be repeated every decade with updated long data records to understand the changes in the extreme inflows in the changing climate. in the changing climate.