A habitat risk assessment determines the susceptibility of a specific habitat to a successful invasion by zebra mussels. In this context, a successful zebra mussel invasion is defined as a zebra mussel introduction that results in the establishment of a viable population of adult mussels. Any predictions must be based on at least a year of reliable physical data.
To aid in determining a risk assessment score, a Risk Assessment Calculator that uses literature value ranges for five physical habitat factors can be used to establish a numerical "habitat score.” The Risk Assessment Calculator recognizes three basic risk categories that are based on a range of habitat scores. These categories are: