Abstract: A method of reconstructing or reclaiming river channels which are partially filled with soft, slimy sedimentary deposits including industrial wastes which are in a semi-fluid condition or fluidized state comprising the steps of: demarcating a portion of the channel by placing a water tight wall entirely across the channel from bank to bank at an upstream and downstream location; depositing stable fill material adjacent the banks of the channel so as to displace the soft sedimentary deposits and water toward the center of the channel; and treating the displaced soft sedimentary deposit in situ beneath the overlying water so as to stabilize the entire mass.The channel may be completely reclaimed by pumping out the overlying water after the soft sedimentary deposit has been stabilized and then filling with stable material or stable material may be simply placed on the stabilized mass and the water displaced over the top of the downstream wall or over the adjacent bank.