The Information Collection Rule (ICR), promulgated on May 14, 1996, requires utilities that meet certain criteria to conduct disinfection byproduct precursor (DBP) removal studies. These treatment studies are designed to evaluate the technical feasibility of using membrane processes (i.e., nanofiltration) and granular activated carbon (GAC) to remove DBP precursors prior to the addition of chlorine based disinfectants. Under the ICR treatment study requirement, results from a total of 99 studies will be submitted, including 62 GAC studies and 37 membranes studies. US Environmental Protection Agency (USEPA) is currently developing a data management system and a data analysis plan for the treatment study results. The data management system will be constructed as a database to organize the complex data sets generated during the treatment studies, and this system will serve as the platform for higher level analyses. The data analysis plan will define the high level analyses necessary to produce information that can feed into the development of the Stage 2 D/DBP regulation. The results from these studies will constitute an unprecedented database which will be used by USEPA and stakeholders to assess the feasibility and cost of using GAC and membrane technologies to control the occurrence of DBPs in a wide range of waters, and this information will be critical in evaluating the Stage 2 D/DBP Rule options. Includes 10 references, tables, figures.