this reduces the areas of low sewage movement and therefore increases the effectiveness of the treatment process fig3 shows a partial cross sectional view of pond 10 the barriers in grid system 24 as well as baffles 26 and 28 are anchored in the side or bank of pond 10 through the use of a plurality of anchor posts 48 and tether lines 50 the use and installation of grid system 24 is described in greater detail in the references incorporated by reference in this application the barriers in grid system 24 are constructed of high density polyethylene or a similar material the barriers are designed to float at midheight within pond 10 and form grids which are small enough to dampen the effect of wind and waves in pond 10 this allows the formation or growth of a stable cover or mat 52 of organic and or inert matter on the surface of the sewage in pond 10 this stable mat reduces heat release and odor release thereby increasing the effectiveness of the sewage treatment process since grid system 24 prevents wind and wave action it also prevents erosion from the banks or berms of pond 10 this further reduces the cost of maintaining pond 10 fig4 shows a second embodiment of a sewage treatment pond 80 of the present invention pond 80 is shown for the sake of clarity with grid system 24 removed pond 80 is a generally circular system having an inlet 82 and an outlet 84 the current flow in pond 80 is indicated by arrows 86.