Mathematical texts describing canal construction and maintenance abound in ancient Mesopotamia, where irrigation was vital to crop production. Indeed, this land’s survival was dependent upon irrigated agriculture. Intensification required new canals, which required the mobilization of significant resources. Old canals required maintenance, or they would silt up. This required planning and so surveyors and administrators needed to learn mathematical processes involved in planning and maintaining irrigation works. This paper examines these mathematical processes. It explores both mathematical texts from the Old Babylonian period (the beginning of the second millennium BCE in southern Iraq), as well as mathematical processes witnessed in administrative texts that deal with irrigation and excavation. It will be seen how well mathematical texts reflected administrative practice when it comes to canal maintenance.