This report summarizes the activities of the NH Department of Environmental Services (NHDES) Shellfish Program for the period of January 2004 to December 2004. The NHDES Shellfish Program conducts a number of activities to minimize the health risks associated with consuming shellfish, and to continue to comply with National Shellfish Sanitation Program guidelines. Among basic program functions is a routine water quality monitoring program, which involved the collection of nearly 800 samples at over 70 sites in 2004, the results of which are used to ensure that assessments of water quality for all areas are kept up-to-date. Weekly red tide monitoring was critical for early detection of dangerous levels of Paralytic Shellfish Poisoning toxin in offshore waters in August, leading a nearly one-month closure to all harvesting in the Atlantic coastal waters. The programs pollution source identification and evaluation program involved the collection of nearly 200 water samples, used to guide proper classification of the receiving waters. A number of other studies and sampling programs, including effluent dilution/dispersion studies of the Newmarket and Dover wastewater treatment facilities, were completed. A particularly useful sampling program has been the initiation of post-rainfall water and shellfish tissue sampling in conditionally approved areas. This program improved management decisions and increased harvesting opportunities in Hampton/Seabrook Harbor, providing data that drove decisions to open the flats on most of the 16 days that the harbor was available for harvesting. Sanitary surveys were completed for Great Bay, and are near completion for Little Bay and the Bellamy River. Surveys for Hampton/Seabrook Harbor, the Cocheco River, Salmon Falls River, and the Upper Piscataqua River have been initiated and are scheduled for completion in 2005.