This project led to the development a parallel processing version of the coupled hydrodynamic and water quality model ELCOM-CAEDYM using the OpenMP (Open Multiprocessing) programming interface. There were a number of key areas of areas of the ELCOM-CAEDYM code where multi-threading was implemented using OpenMP. These were the scalar transport, vertical mixing model, momentum and free surface solutions. The project led to a speed up of over 10 times the previous version of ELCOM- CAEDYM.