Distribution on aquatic macrophytes has been studied down the drainage channel, in the irrigated area of 'La Violada' (Huesca, Spain). In the affinity analysis we detect two groups of macrophytes: the helophytes and the limnophytes. Data on chemical composition of water, Ca2+,Mg2+,Na+,K+, electric conductivity, and water flow are included. With regard to its chemical features and its type of vegetation, the channel may be regarded as failing into three zones. The specie with the most homogeneous distribution is Phragmites communis and the most abundant lymnophyte along the drainage channel is Potemogeton pectinatus.