Over the recent years, managers of the Algerian National Sanitation Office (ONA) have been worrying about the degraded state of their Urban Drainage Systems (UDS). This infrastructure failure is due essentially to the lack of funding and absence of adequate structured methodology for diagnosis and maintenance. As a result, ONA's managers found it very interesting to get a tool that allows them to assess their management of UDS operation. The aim of this paper is therefore to provide an assessment tool to managers for a good network operation. The adopted approach is participative and takes into account the specific local context. Six performance indicators, grouped into two criteria, have been constructed to achieve this objective. These indicators have been chosen for their effectiveness; they are scaled to get their performance scores according to a scaling constructed here based on standards when available and to the ONA expert's recommendations. The developed tool is applied to the UDS of Bejaia City, in north-eastern Algeria. The assessment and the analysis of the performance evolution of these indicators for the period 2017-2021 are carried out. The results highlighted successes that can be maintained as well as weaknesses that need to be improved.