This report presents the results of a study to determine whether shallow ground water at Picatinny Arsenal Morris County, New Jersey, has been con- taminated as a result of operations at the open burning area, which is used for burning of waste explosives and materials contaminated with explosives. Results of previous investigations indicate that the soil in this area is contaminated with metals and organic compounds. Twenty-seven wells were sampled for analysis for inorganic constituents, nutrients, and explosive compounds. Selected wells also were sampled for analysis for base/neutral- and acid-extractable compounds, pesticides, volatile organic compounds, and dioxin and furan compounds. Surface-water and streambed- material samples were collected at three sites in Green Pond Brook. Water-level measurements indicate that ground-water flow generally is nearly horizontal and toward Green Pond Brook. The average velocity of the ground water is estimated to be 0.03 to 1.8 feet per day. Concentrations of iron and manganese in ground-water samples from the unconfined aquifer were consistently greater than U.S. Environmental Protection Agency secondary drinking-water regulations. Because similarly high concentrations of these constituents have been found in ground-water samples at the arsenal, they are not considered to be a consequence of activities at the open burning area. Contaminants from the open burning area appear to be contributing to elevated concentratons of lead, zinc, and explosive com- pounds found in the streambed material. Other trace element and polynuclear aromatic hydrocarbons probably are derived from both the open burning area and upstream sources. Volatile organic compounds were detected in surface-water samples at low concentrations, although most were found upstream from the open burning area. No inorganic or organic constituents were detected in ground-water or surface-water samples in concentrations that exceeded U.S. Environmental Protection Agency primary drinking-water regulations.