Concentrations of copper in water rose rapidly following the introduction of boats to a new marina in San Diego Bay. Two months after the marina reached half its capacity, a majority of water samples exceeded chronic and acute criteria for dissolved copper, and copper concentrations in several samples exceeded the highest concentrations observed in another marina that has been listed as an impaired water body. A box model suggested that a small fraction of the leached copper was sequestered in sediment. Copper concentrations in water entering the marina from the bay was more than half the chronic concentration limit, so only 50% of marina boat capacity could be accommodated without exceeding the chronic criterion more than 50% of the time. Copper concentrations in water may increase rapidly following boat introduction in small marinas, but could return to pre-introduction levels by controlling boat numbers or reducing use of copper-based paints.

Defining subsystems by using FD can lead to poor architectural concepts FD alone cannot be used to determine whether the subsystems will provide common functionalities that could be used across many requirements. Using functional decomposition /allocation to create architecture, can produce subsystems with duplicate functionality Designing subsystems with duplicate functionalities will create unnecessarily large and complex systems The logical functional decomposition enables – Realization that multiple system functions/requirements can be met by each component or subsystem – Formulation of alternate functional concepts; e. g. utilizing subsystems interactions to meet several system requirements Subsystems should, ideally, provide services in a "one- to-many, many-to-one" relationship: – One system requirement can be decompose into many subsystem requirements – One subsystem requirement may be derived from many system requirements – The approach to subsystems service definition is a form of functional decomposition (determining subsystems first, and then deriving their requirements)