The mpC language was developed to write efficient and portable programs for wide range of distributed memory machines. It supports both task and data parallelism, allows both static and dynamic process and communication structures, enables optimizations aimed at both communication and computation, and supports modular parallel programming and the development of a library of parallel programs. The language is an ANSI C superset based on the notion of network comprising processor nodes of different types and performances, connected with links of different bandwidths. The user can describe a network topology, create and discard networks, distribute data and computations over networks. The mpC programming environment uses the topological information in run time to ensure the efficient execution of the application. The paper describes the implementation of managing networks in the mpC programming environment.