The Collaborative International Dictionary of English v.0.48:

overutilization \overutilization\ n.
   exploitation to the point of diminishing returns.

   Syn: overexploitation, overuse, overutilisation.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

overutilization
    n 1: exploitation to the point of diminishing returns [syn:
         overexploitation, overuse, overutilization,
         overutilisation]