A system, methodology, and programming logic for active stormwater controls to optimize sizing and design of Hydromodification Management (HM) structural Best Management Practices (BMPs) to achieve optimal flow duration control. Control logic enables the controlled release of stormwater from a BMP in a manner most akin to pre-development flow duration curves. Inputs to this logic include: flow duration curves based on continuous hydrologic simulation for pre- and post-development conditions; real-time measurement of water level within the BMP; and real-time measurement of discharge entering the BMP. This control logic can interact with control logic for other stormwater management objectives, such as harvest and reuse, infiltration, and combined sewer overflow prevention, and respective inputs, such as real-time weather forecast data, precipitation gage data, downstream flow gauge data, and water quality data, to meet those design objectives as well. New HM BMPs can be optimized to be smaller and, thus, more feasible to implement. Existing stormwater facilities designed for flood control or other management objectives can be retrofitted to provide hydromodification control as well. When utilized with real-time flow and water level monitoring equipment and data, the flow release logic can be adaptively adjusted without physical retrofit of the BMP's outlet.