There is described a fluid treatment system. The fluid treatment system comprises: an open channel for receiving a flow of fluid and a fluid treatment zone. The fluid treatment zone comprising a plurality of elongate radiation source assemblies orientated such that: (i) a longitudinal axis of each radiation source assembly is transverse to a direction of fluid flow through the fluid treatment zone, and (ii) an end of each radiation source assembly is disposed above a predetermined maximum height of fluid flow in the open channel. A first baffle plate is disposed upstream of the fluid treatment zone. The first baffle plate is positioned such that a distal end thereof is below the predetermined maximum height of fluid flow in the open channel. In a preferred embodiment, the present fluid treatment system provides for an area in which a cleaning system for the radiation source assemblies can be “parked” when not in use. In the so-called “parked” position, the cleaning system may be readily accessed for servicing and the like without affecting the flow of fluid through the fluid treatment zone and a fluid treatment system. This is as significant advantage of the fluid treatment system.