The proposal of this work is the classification of medium and large rivers, followed by the delimitation of the Permanent Protection Areas (APP) in each margin of the river, finishing with the classification and evaluation of the land use in these APPs. The object of analysis is an area of the city of São José dos Campos located in the Paraíba do Sul river basin characterized as having great influence on the water supply and economy of the states through which it travels. The study area was chosen in partnership with the Chico Mendes Institute (ICMBio) and attending research interests of INPE. The delimitation of the river it was accomplished through automatic classification of images from the RapidEye satellite provided by the Ministry of the Environment (MMA), based on the Matiz component of the transformation of the RGB color space to HIS. The macrófitas areas were incorporated into the river by manual editing. The APPs, in agreement with new forest code, were drawn considering the river automatically with and without the macrófitas. The result of the comparison of areas between the two representations showed the importance of the macrófitas to be considered for the final calculation of the APPs, because the area within the river increased 31.4% and APPs 17.9%.