In developing revised water quality criteria, designated uses, and boundaries for those uses toprotect living resources in the Chesapeake Bay and its tidal waters, the Environment ProtectionAgencys (EPA) Chesapeake Bay Program Office provided to Bay jurisdictions information fordevelopment of water quality standards for dissolved oxygen, clarity, and chlorophyll a in itsguidance document Technical Support Document for Identification of Chesapeake BayDesignated Uses and Attainability (Technical Support Document) (U.S. EPA Chesapeake BayProgram. 2003.). Part of the jurisdictions water quality standards development process may be to conduct use attainability analyses (UAAs). The information contained in the Technical Support Document is to assist states in development of their individual UAAs, and serve as a basis for state-specific documents that will be initiated after the revised criteria for the Chesapeake Bay are finalized by EPA. This document supplements the Technical Support Document by presenting economic analysesperformed by the Chesapeake Bay Program related to controls to meet the revised criteria anduses. Part I of the Economic Analyses provides estimates of the total annual cost of achieving the three levels of controls based on the costs of best management practices (BMPs) to remove nitrogen and phosphorus loads to the Chesapeake Bay. This cost information includes totalcapital cost requirements, and to the extent that information could be compiled, estimates of how these costs may be shared between the public and private sectors. Part II describes economic modeling of the potential impacts of these control costs in the Bay region. Part III documents a screening-level analysis of potential impacts, also based on the costs of the tier scenarios. Although this information may be useful to states in developing their own UAAs, the Bay Program did not use these analyses to delineate boundaries for the new refined designated uses.