The discharges of pollutants originating from stormwater runoff (SWR) and combined sewer overows (CSOs) were dealt with in Chapters 4 and 5, respectively. In Chapter 6, the effects of these discharges will be focused on. In very general terms, the urban wet weather effects are briey described in Section 1.3 and outlined in Table 1.1. In particular, the general characteristics in terms of time and spatial effects of pollutants like acute and accumulative effects are dealt with in Section 1.3.2. The different types and characteristics as well as the extent of these effects are central for why and how to manage and control the wet weather discharges. This chapter is, in this respect, a prerequisite for the following chapters focusing on engineering solutions to the wet weather discharges.