The present paper deals with the design of a controller focused to the automatic control of hydraulic canals. The designed controller will be required to be robust to large changes in the time delay as well as in all other parameters of the model, such as static gain and time constants. The methodology developed here is based on fractional order PI controllers (FPI), which have proven to be more robust than classical PI controllers, by virtue of the extra λ parameter (fractional order) that permits it to fulfill additional specifications. The results obtained will be compared with another FPI designed specifically to be robust to changes in all the parameters, except time delay, which is considered constant.