Abdurazak Mohammed (PhD)Henok Girma2025-07-302025-07-302024-10https://etd.aau.edu.et/handle/123456789/5740This study examines the causes of delays in wastewater treatment plant construction projects overseen by the Ethiopian Engineering Corporation. The research focuses on projects including Ziway Federal Prison WWTP, Dire Dawa Federal Prison WWTP, Bole Arabsa WWTP, and Ambo University WWTP. By distributing questionnaires to stakeholders such as clients, contractors, and consultants, an explanatory research approach was employed to establish the cause and effect relationship between variables like poor planning, price escalation, late delivery of construction material, inefficient machinery, and external factors. Utilizing SPSS 20 software for data analysis (including normality tests, correlation, and regression analysis), the study identified correlations between these factors and project delays. The findings emphasize the importance of proactive measures to ensure timely completion and project efficiency, recommending a comprehensive and proactive project management approach for successful outcomes in EEC-managed WWTP projects. Key word: Project delay, delay factor, wastewater treatment plant, constructionen-USThesis