This research aimed at the performance assessment of small dams for effective small dam performance index modeling. From the implementation report of water source network (PJSA) river area institution NT II, 2022, it is known that from the 22 regencies where are in the Nusa Tenggara, there are 321 small dams have been assessed for knowing the percentage average of damage to the small dams. From the three islands that are chosen as the research locations, it is known that the regency that has the highest average percentage of damage is the Ende regency located on the Flores Island. The methodology consists of: 1) Studying literature on the performance model that has been developed and the performance factors that are affected; 2) Analyzing the data and the small dam condition; 3) Drafting the parameter of the small dam performance index parameter. The results show that the average physical condition of small dams in the Nusa Tenggara Timur is moderate: 61-80% out of 100%, which is a good small dam condition. The average condition of small dam operation and maintenance performance in the Nusa Tenggara Timur is atrocious: 39% out of 100%. The average condition of small dam organization management in the Nusa Tenggara Timur is atrocious because there is no group of small dam water users. This result can be used for supporting the modeling of the small dam performance index in the semi-arid area as the validation scheme. Small dams are one of the water sources that very help fulfilling the water need in the Nusa Tenggara Timur region, and the amount is high enough until 2020; there are 3,658 small dams. Keywords : assessment, small dams, condition, semi-arid area. https://doi.org/10.55463/issn.1674-2974.50.3.8