In December of 2000, EPA Headquarters (HQ) circulated a memorandum to its Regional offices requesting feedback on issues relating to the implementation of its drinking water regulations. Although the memorandum specified a 'potential set of issues' for consideration, Regions were asked to identify any other known issues related to regulatory implementation. In addition, the Association of State Drinking Water Administrators (ASDWA) was asked to confer with the States regarding implementation issues that they felt needed to be reviewed or addressed. The number and extent of responses from EPA Regions and States were limited. In response to the memorandum and the request to the ASDWA, EPA received feedback from: nine EPA Regions, seven States, and ASDWA. Of the written communications received, a few discussed issues that have already been addressed in the recently published arsenic and radionuclides NPDWRs (66 FR 6975, January 22, 2001 (USEPA, 2001); 65 FR 76707, December 3, 2000 (USEPA, 2000b)), and others are being addressed through ongoing mechanisms. This document summarizes the implementation issues that were discussed in this written (and some verbal) feedback from EPA Regions and States.