NOVELTY - A controlled eutrophication system includes an inlet in fluid communication with algal growth channel; a first flowrate control device for controlling the flowrate of water through the channel; raceway(s) containing a first aquatic organism; a second flow rate control device for controlling the flowrate of water through the raceway; a polishing chamber containing a second aquatic organism; biomass removal device; and water discharge.    USE - For removing pollutants or other contaminants from wastewater or runoff water stream.    ADVANTAGE - The invention allows for increased algal productivities, increased fish output per unit production area, a reduction in feed inputs and a reduction in aeration power consumption.    DETAILED DESCRIPTION - A controlled eutrophication system comprises an inlet in fluid communication with an algal growth channel (14), and a first flowrate control device (16) for controlling the flowrate of water through the algal growth channel.    Raceway(s) (22) is in fluid communication with the algal growth channel.    The raceway contains a first aquatic organism that consumes algae and excretes an algal biomass. A second flowrate control device (28) is provided for controlling the flowrate of water through the raceway. A polishing chamber (24) containing a second aquatic organism that consumes algae and excretes an algal biomass is provided. A biomass removal device is provided for removing algal biomass from the raceway and the polishing chamber.    A discharge is in fluid communication with the polishing chamber for discharging water to an external water source having reduced levels of algae.    INDEPENDENT CLAIMS are also included for:    (a) producing a hydrocarbon from a biomass comprising mixing biomass with a cellulose source (20-60 wt.%) in a digester, the cellulose, heating the mixture to at least 30 degrees C, and collecting a hydrocarbon gas from the digester; and    (b) a controlled eutrophication process comprising flowing a wastewater containing a waste component comprising nitrogen and/or phosphorus into an algal growth channel, contacting the wastewater with a species of algae in the algal growth channel, flowing a first portion of the algal laden water from the algal growth channel to a raceway containing a first aquatic organism, flowing a second portion of algal laden water from the algal growth channel is flowed to a polishing chamber containing a second aquatic organism, discharging water from the polishing chamber to an external water source, and collecting the algal biomass from the raceway and the polishing chamber.    The algae consumes and depletes the waste component from the wastewater.    The first aquatic organism consumes the algae in the water and excretes an algal biomass.    The second aquatic organism consumes at least 60% of the algae contained in the water, and excretes an algal biomass source.    DESCRIPTION OF DRAWING(S) - The figure is an isometric view of a partitioned aquaculture system for use in a controlled eutrophication system.    Algal growth channel (14)    Flowrate control devices (16, 28)    Common channel (20)    Raceway (22)    Polishing chamber (24)    Containment sections (32, 34)    Conveyor (36)