ABSTRACT. – This study was designed to evaluate the utility of current monitoring metrics in short coastal streams in the north of Spain by collecting chemical, physical and biological data from a watershed affected by agriculture and tourism. Also, as there are hardly any data on benthic macroinvertebrate assemblages in this type of water course, the use of biotic indices and other systems for identifying bioindicators in such an unusual habitat as the one in question can be validated. IBMWP accurately detects impacts and environmental changes in this type of watercourse, which is unusual due to its small dimensions and relatively poor invertebrate community as it obtains an identical response in the two annual cycles studied and detects environmental changes reliably. IASPT, H’ or family richness also detect these changes, though less accurately. The echinogammarus:Proasellus ratio –adapted to the local fauna from Gammarus:asellus index- could be used in addition to this metric or others, or for biomonitoring individual sites.