Abstract: A hydraulic diverter comprises a pair of tubes connected to receive water from a storm drain. One of the tubes is connected to discharge the water into a basin, while the other is connected to discharge water and bed sediment load into a bypass line. The storm water flow is preferentially directed through one tube or the other by changing the relative elevations of the tubes. The tubes are coupled together to change elevations by a pulley system or a swivel system. The pollutant laden "first flush" flow of storm water is diverted to the basin, while subsequent or "sustained" flow transporting bed sediment load is directed through the bypass line. The storm water itself is utilized to change the relative elevations of the tubes when the storm water flow transitions from a first flush flow to a sustained flow.