On 5 April 1999 the Office of the Chief of Naval Operations (CNO) issued the Navy Policy for Conducting Ecological Risk Assessments. The purpose of this policy, which amplifies the 16 May 1997 Assistant Secretary of the Navy (ASN) Environmental Policy Memorandum 97-04, Use of Ecological Risk Assessments, is to provide clarification of the Navy's policy on ecological risk assessments (ERAs) and the manner in which ERAs are to be implemented for the Navy in the Installation Restoration (IR) Program. The overarching goal of the Navy policy is that ERAs conducted for the Navy are scientifically based, defensible, and done in a manner that is cost effective and protective of human health and the environment.