This paper discusses the deterioration of indigenous irrigation system traditionally developed in the past to serve the peri-urban agricultural lands that have been affected by rapid urbanization in the Bangkok Metropolitan Region. The study is based on data collection from mapping, field survey and interview analyses and identifies current canal deteriorating conditions in four categories: filled, covered, narrowed and shallow, and normal. The findings reveal that different types of canal deteriorations are associated with their private ownership. A typology of land configurations of urban and non-urban land uses along private canals is pointed out in order to understand their relation with canal deterioration types. Caused by urbanization, the degradation of the existing canal networks has provoked conflicts between local farmers and new proprietors, especially real estate developers. Such canal deterioration essentially reduces their ability to convey a water supply to feed agricultural lands, consequently leading to the discontinuation of land use for agriculture and its eventual transformation into urban developments.