Essex an Suffolk Water (ESW) and the Environment Agency, Anglian Region, are carrying out a joint project to develop a new computer-based numerical model of the Ely Ouse - Essex Transfer Scheme (including the ESW reservoirs at Hanningfield and Abberton). ESW, as part of this project, is commissioning an investigation of the River Stour and the River Blackwater to improve the level of understanding of key aspects of their hydrology affecting operation of the transfer. This document summarises the project brief, it does not contain any measurements.