Groundwater performs an important role in the territory of the plains Garmsar. In this study, on the basis of water samples, which were obtained from the wells of the region, assessment of groundwater quality was carried by piezometric and a map of contamination of the water has been made in the software of ArcGIS. Zoning maps were prepared in the ArcGIS software for assessment of water quality after collection of statistical data and choosing the best interpolation method to estimate better tendency to change. The results showed that in addition to the parameters of chlorine in the period from 2002 to 2011, concentration of elements was reduced and we were surprised by this, as should be the opposite. At the same time, geological study of the region showed that the salinity of the upper layers of the earth’s surface is larger than the bottom, and as the water level in the period from 2002 to 2011 has been decreased, it can be assumed that the water quality was improved.