This paper presents CORD, a reliable bulk data dissemination protocol for propagating a large data object to all the nodes in a large scale sensor network. Unlike well- known reliable data dissemination protocols such as Deluge whose primary design criterion is to reduce the latency of object propagation, CORD's primary goal is to minimize energy consumption. To achieve its goals CORD employs a two phase approach in which the object is delivered to a subset of nodes in the network that form a connected dominating set in the first phase, and to the remaining nodes in the second phase. Further, CORD installs a coordinated sleep schedule on the nodes in the network whereby nodes that are not involved in receiving or transmitting data can turn off their radios to reduce their energy consumption. We evaluated the performance of CORD experimentally on both an indoor and outdoor sensor network testbed and via extensive simulations. Our results show that in comparison to Deluge (the de facto network reprogramming protocol for TinyOS) CORD significantly reduces the energy consumption for reliable data dissemination while achieving a comparable latency.