We propose a simple parallel algorithm for finding a blocking flow in an acyclic network. On an n-vertex, m-arc network, our algorithm runs in O(n log n) time and O(nm) space using an m-processor EREW PRAM. A consequence of our algorithm is an O(n2(log n) log(nC))-time, O(nm)-space, m-processor algorithm for the minimum-cost circulation problem, on a network with integer arc capacities of magnitude at most C.