Apparatus for removing materials settling in or suspended in liquid in a liquid reservoir, said apparatus comprising: a float assembly including a frame, a suction head assembly, said suction head assembly including: a support frame, an elongated suction head mounted to the support frame, said suction head having a hollow interior and an open lower side defining an entrance mouth, and a suction pump mounted to said suction head and being adapted to communicate with said hollow interior of the suction head, said suction pump being operable to create a suction pressure in said suction head to draw in said materials through said mouth and pump said materials to an on land location, at least one elongated guide member between said suction head assembly and said float assembly disposed in an upright attitude for vertical guided movement of said suction head assembly towards and away from said float assembly, said at least one elongated member being pivotally connected at its lower end to one end of said suction head assembly, at least one slide means on said float assembly through which said at least one elongated member is captured and guided to said float assembly and permits said suction head assembly to be raised and lowered relative to said float assembly, a means for raising or lowering said suction head assembly in a substantially vertical movement relative to said float assembly, said raising and lowering means supporting and permitting operation of said suction head between a raised position in which said suction head assembly is located adjacent said float assembly and a lowered position in which said suction head assembly is positioned substantially beneath said float assembly and is adjacent to a floor surface of said reservoir and intermediate positions between said raised and lowered positions, said apparatus being characterised by said at least one upright elongated member comprising depth markings on said upright member for visually indicating the depth of operation of said suction head assembly, said float assembly being supported on skids, and said suction head assembly further including skids. a float assembly including a frame, a suction head assembly, said suction head assembly including: a support frame, an elongated suction head mounted to the support frame, said suction head having a hollow interior and an open lower side defining an entrance mouth, and a suction pump mounted to said suction head and being adapted to communicate with said hollow interior of the suction head, said suction pump being operable to create a suction pressure in said suction head to draw in said materials through said mouth and pump said materials to an on land location, a support frame, an elongated suction head mounted to the support frame, said suction head having a hollow interior and an open lower side defining an entrance mouth, and a suction pump mounted to said suction head and being adapted to communicate with said hollow interior of the suction head, said suction pump being operable to create a suction pressure in said suction head to draw in said materials through said mouth and pump said materials to an on land location, at least one elongated guide member between said suction head assembly and said float assembly disposed in an upright attitude for vertical guided movement of said suction head assembly towards and away from said float assembly, said at least one elongated member being pivotally connected at its lower end to one end of said suction head assembly, at least one slide means on said float assembly through which said at least one elongated member is captured and guided to said float assembly and permits said suction head assembly to be raised and lowered relative to said float assembly, a means for raising or lowering said suction head assembly in a substantially vertical movement relative to said float assembly, said raising and lowering means supporting and permitting operation of said suction head between a raised position in which said suction head assembly is located adjacent said float assembly and a lowered position in which said suction head assembly is positioned substantially beneath said float assembly and is adjacent to a floor surface of said reservoir and intermediate positions between said raised and lowered positions, said apparatus being characterised by said at least one upright elongated member comprising depth markings on said upright member for visually indicating the depth of operation of said suction head assembly, said float assembly being supported on skids, and said suction head assembly further including skids.