EFFECT OF RAINFALL ON GIARDIA AND CRYPTO

An investigation of the variability of concentrations of Giardia cysts and Cryptosporidium oocysts in the Delaware River was conducted in 19 96 at Trenton, N.J. A goal of the study was to examine the relationshi p between concentrations of Giardia and Cryptosporidium and a variety of more easily measured microbial, water quality, and meteorological p arameters. A positive correlation (Spearman rank; p < 0.05) was demons trated between concentrations Giardia cysts or Cryptosporidium oocysts and 15 other parameters. Increased concentrations of Giardia and Cryp tosporidium as well as a variety of other microorganisms were associat ed with rainfall. The effect of rain fall on parasite concentrations i s due in part to increased particulate matter in the water column foll owing surface runoff and resuspension of river bottom and storm drain sediment.