• Microseismic monitoring arrays are required to detect the smallest possible event, or to guarantee detection of an event of some minimum size. Diverse geometries and performance metrics have been proposed over the years. Existing methods underestimate or neglect completely the spatial variation of site noise. A simple method is developed for comparing the performance of one array geometry to another which does take the variation of site noise with geography into account. A case study from a recent site survey in Duchesne County, Utah is included to show how such an array metric might work in practice. With such tools in hand for assessing array performance it becomes possible to assess array performance as the sensors are being installed, thus maximizing performance while minimizing installation effort.