Energy constraints have had a significant impact on the design and operation of wireless sensor networks. In this paper, we investigate base station selection (or anycast) problem in wireless sensor networks. We consider a wireless sensor network having multiple base stations (data sink nodes), where each source node must send all its locally generated data to only one base station. To maximize the network lifetime, it is essential to optimally match each source node to a particular base station in addition to finding an optimal routing solution. We propose a polynomial time heuristic for optimal base station selection for anycast via a sequential fixing procedure, under the assumption that the bit rate from each source node is constant. Through extensive simulation results, we show that this heuristic has excellent performance behavior and is a tight low bound that is very close to optimal solution for the original optimization problem.