1792) Cage Farms: Almus Reservoir (Tokat) IntroductıonIn recent years, a substantial world -wide increase in intensive aquaculture has led to an increase in awareness of the environmental impacts of fish farming, with increased importance given to sustainable farming.The negative effect on sediment in receiving environments caused by the input of nutrients from cage farms is increasingly significant in terms of water quality.Addditionally, the reversal of possible changes in the sediment chemistry takes more time when co mpared to changes in the water.Monitoring the sediment-oriented environ mental effects of cage culture is important in determining at an early stage the potential unacceptable effects of farming on the receiving environ ment and taking necessary measures (La Rosa et al., 2004;Soto and Norambuena, 2004).Rainbow trout farming is the most prevalent type of freshwater aquaculture in Turkey, and reservoirs have an important potential with regard to freshwater aquaculture products.The MOM (Modelling-Ongoing fish farms-Monitoring) system was developed to control the impact of organic waste fro m marine fish farms in Norway, but it is based on a general concept of environmental management and may be adapted to other fish species and inland waters (Anonymous, 2000).The MOM system is composed of a model and an observation program includ ing Environmental Quality Standards (EQS).The observation program has three investigation types: A, B and C. The A-investigation takes basic measurements of the proportions of organic material in the sediment below the cage operation.The Binvestigation is conducted in the local impact zone and includes parameters of three groups.Finally, the C-investigation is concerned with the benthic community structure in the mid-and regional-impact zones (Hansen et al., 2001;Stigebrandt et al., 2004).The B-investigation type, which is used in the measurement of the local impact of cage operations and combines three group parameters (b iological, chemical, sensory), is preferred by v irtue of its ease of use, ability to be applied frequently and possibility of use in areas of concentrated environmental impact.Co mbin ing more than one of these parameters rather than using one of them alone increases the reliability of the evaluations and min imizes errors resulting fro m differing measurements.