The DGRM is therefore responsible for carrying out maintenance dredges to ensure navigability in the following ports: Vila Praia de Âncora, Castelo de Neiva, Esposende, Póvoa de Varzim, Vila do Conde, Angeiras, Nazaré, S. Martinho do Porto , Peniche, Ericeira, Baleeira, Lagos, Alvor, fishing port, shipyards and Ferragudo area in Lagoa, Marina de Portimão and Arade river basin, Albufeira, Vilamoura, Quarteira, Faro (except commercial port area and access channel ), Olhão, Fuseta and Tavira, and existing infrastructure on the Guadiana River between Vila Real de S. António and Mértola.
The maintenance dredging takes on greater expression in the ports of the north and centre of the country, subject to sea conditions and more agitated sea agitation and with tidal currents with greater capacity of sedimentary transport, frequently promoting the silting of the bars and navigation channels.
Preceding dredging and in compliance with Administrative Rule no. 1450/2007, of November 12, the DGRM carries out sampling campaigns for particle and physicochemical characterization of the sediments to be dredged and identification of the respective levels / classes of contamination. The frequency of sampling and the number of samples are carried out in accordance with the stipulated in said ordinance.