MICROBIOLOGICAL QUALITY OF SHELLFISH-GROWING WATERS IN CHESAPEAKE BAY

A total of 338 water samples were collected at 20 stations from three geographically shellfish-growing areas in Chesapeake Bay from May to S eptember 1989. Samples were examined for standard plate count, total c oliforms, fecal coliforms, Escherichia coli and coliphages. Salinity, dissolved oxygen and temperature varied slightly with the depth, seaso n, and geographic area of water samples. The geometric means of standa rd plate count for the three areas were 135, 355 and 275/ml, respectiv ely. The range of means of fecal coliform for these areas was from <3 to 93/100 ml. Escherichia coli counts were also low with a range of <3 to 93/100 ml and a mean of <3/100 ml. The growing water area adjacent to cropland was found to have higher bacterial counts than those of t he other two areas. Levels of male-specific phages were very low. Resu lts indicate that shellfish-growing waters in all three areas were of satisfactory bacteriological quality.