The purpose of this report is to strengthen the groundwater section of the proposed set of Environmental Performance Indicators for monitoring air, freshwater, and land. The development of these indicators is described in a discussion document, Environmental Performance Indicators - Proposals for air, fresh water, and land (MfE, 1997), and their purpose is for monitoring progress towards achieving the environmental goals specified in the document, Environment 2010 (MfE, 1995). The review process that followed publication of the proposed indicators concluded that the groundwater section required strengthening.