Maps DR
The Geographical Survey is now located in the Feria, on the Avenida Churchill next to the French School, near the Malecon. The DR govt has been working on mapping the whole country for the last ten years. The project is not completed but if you are lucky they could have completed the area you are interested in. The maps are of excellent quality and at the best prices.
Your other option is Mapas Gaar in El Conde #502, Zona Colonial, SD tel 688-8004 They have the most comprehensive selection of maps of the DR