Surface-water samples were collected on a monthly basis for the period April 1981-March 1982 from six sites within the Barataria Marsh Unit of the Jean Lafitte National Historic Park, Louisiana. The sites were located on Bayou Segnette, Kenta Canal , and Millaudon Canal. Biological, chemical, and physical analyses were performed. Three of the sites were sampled quarterly for additional parameters including pesticides, metals , algal-growth potential, phytoplankton, benthic invertebrates, and grain size of bed material. The results of the analyses are presented without interpretation. (USGS)