T0078 A303 Cartgate Reservoir Feasibility

The flood storage bund, which creates the reservoir as seen today, was constructed circa 1987 as part of the new A303 London to Penzance Trunk Road (Ilchester to South Petherton section). The embankment and spillway were constructed on the line of the dismantled GWR Durston & Yeovil Branch railway line (the embankment being re-placed and the control structure being located on the line of an existing culvert through the railway embankment). As the trunk road does not discharge into the reservoir catchment, the intended purpose/benefit of the flood storage area is not known. It is possible that the original railway culvert restricted and caused attenuation of flood flows and, with the development of the Cartgate picnic area, the works were undertaken to compensate for the loss of area by allowing a greater depth of storage (and to manage spilling during extreme events).