If a developer does not want to pay the contribution, all runoff from the development would have to be stored on the development site with no outfall into the ordinary watercourse or any drainage system which will convey the water to the Board’s District. Alternatively, where developers are confident that their drainage design reduces the rate and volume of surface water downstream, they should provide evidence of this in the form of flow hydrographs at the location of each discharge point for the pre- and post-development scenarios. These should demonstrate that there is no change to the areas under the graph (volume) between the pre and post development scenarios.