In order to produce a large amount of electricity at a competitive cost, farms of Wave Energy Converters (WECs) will need to be deployed in the ocean. Due to hydrodynamic interaction between the devices, the geometric layout of the farm will influence the power production and affect the surrounding area around the WECs. Therefore it is essential to model both the near field effects and far field effects of the WEC farm. It is difficult, however, to model both, employing a single numerical model that offers the desired precision at a reasonable computational cost. The objective of this paper is to present a coupling methodology that will allow for the accurate modelling of both phenomena at a reasonably low computational cost. The one-way coupling proposed is between the Boundary Element Method (BEM) solver NEMOH, and the depth-averaged mild-slope wave propagation model, MILDwave. In the presented cases, NEMOH is used to resolve the near field effects whilst MILDwave is used to determine the far field effects.