Water retention/detention structure formed from identical panels

A system for retaining and detaining water, comprising:

• a plurality of substantially identical panels arranged adjacent to each other to form an assembly with a hollow interior, said panels characterized by
• a front and back surface;
• said front and back planar surface being spaced to define the width of said panels;
• four sides of substantially similar length which define edges of the panels, said sides being disposed at ninety degrees relative to each adjacent side;
• and
• connector tabs extending laterally in substantially identical arrangement from each of four sides of said panels;
• the tabs of at least one panel communicating with the tabs of at least one other panel for the alignment of panels;
• said panel characterized by a plurality of connector tabs extending from each of said side surfaces and a plurality of connector openings at each of said side surfaces;
• said tabs and said openings being defined by having essentially the same length whereby said tab fits within said opening;
• said tabs and said opening being further defined by a square cross section.