During oil and natural gas recovery, substantial volumes of wastewater are generated that must be suitably disposed of. There are two basic options: surface treatment and subsequent discharge of the wastewater, or underground injection in deep geological formations, including depleted oil and gas fields. Although there are fairly standard and widely accepted disposal methods for most of these wastewater flows, certain sector-specific wastewater flows not originating in deep underground need to be legislated more thoroughly. Standard practices for environmental impact assessment were not developed with underground disposal in mind, nor can they be used to that end. The Dutch oil company NAM therefore commissioned CE to develop a method for comparing the environmental impact of deep-well injection with that of alternative disposal options. The method is intended for use in licensing procedures, including EIA procedures, for projects involving injection of wastewater flows from gas and oil recovery. In developing the method, standing policy was taken as the point of departure wherever possible and consultations were held with all the parties potentially involved in such licensing procedures. The next step is to put the method through practical trials in one or more EIA procedures. If the results are satisfactory, it is recommended that the method be adopted as standard procedure.