The reservoir of Keban Dam is a very deep and large water body of temperate zone exhibiting special characteristics with respect to its limnological properties. One of the major characteristics is the development and seasonal persistence of metalimnetic oxygen minima. This characteristic has been observed for three consecutive years. Spatial heterogeneity with respect to several parameters was another distinct property that has been clearly identified. The long term study has identified the existence of an order in the behavior. The modeling for strategy development seems to be a very useful tool to assess the major system variables to be controlled and to achieve comparative evaluation of possible management practices.