Following the presentation to the steering group of the Phase I report, the group agreed that Behavioural Analysis was the best approach to the assessment of surface water yields. Phase II of the project thus became an application of this method to stand-alone direct supply reservoirs. The specific terms of reference are given in Chapter 1. The data sets used in this part of the study were for Vymwy, Stocks, Ely Ouse, Exe, Font, Cray, Elan and Taf Fechan. These were all long records, mostly representing the wetter regions of England and Wales, but with Ely Ouse providing data from the drier South East. The records from Vymwy, Stocks and Ely Ouse were used in behaviour analyses to examine yield-storage relationships, and the effect of the length of record on those relationships. The data for the Elan, Cray and Taf Fechan, and the reconstructed Exe record were used in a comparison of the severity of the 1933/34 and 1975/76 droughts in the south western area of the country. The analyses showed the value of behaviour analysis, revealing important facets of reservoir management that would have remained hidden using other assessment techniques.