A dredging apparatus for dredging waterways containing sediment includes a hood having a passage for water and sediment to enter the hood under the influence of a submersible dredge pump apparatus. The dredge pump apparatus includes an inlet line having an inlet opening positioned in the passage of the hood, and an outlet line which communicates with the inlet line and extends exteriorly to a spoil collection area. A dredge pump draws water and sediment from within the passage into the inlet opening and through the inlet and outlet lines. To prevent clogging of the inlet line by sediment and ensure a continuous dredging operation, replacement water is introduced adjacent to the inlet opening from a water source in response to sensed pressure variations in the inlet line caused by the onset of clogging. A closed dredging circuit is created by using the spoil collection area as the source of replacement water.

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