The study was conducted from November 2021 to May 2022 at the three study sites within the Baghdad governorate. The study aims to identify the impact of human activities on the Tigris River, so an area free of human activities was chosen and represented the first site. A total of 48 types were diagnosed, 6204 ind/m3 spread over three sites. The following environmental indicators were evaluated: Constancy Index (S), Relative abundance index (Ra), Richness Index (between 17.995 and 23.251), Shannon Weiner Index (0.48-1.25 bit/ind.), Uniformity Index (0.124 -0.323). The study showed that the highest percentage recorded was for the phylum Annileda 34%; and the stability index shows that taxes (Stylaria sp., Aoelosoma sp., Branchinra sowerby, Chrironomidae sp.) found by 100%, the relative abundance index show that taxes: Seinura sp. 46% in site 2; other nematodes - 43% in site 3 and 42% in site 1; and Physa sp. 41% in site 1). The physical and chemical factors were measured BOD between (4.4- 1 mg L-1), DO (10.3-8.3 mg L-1), E.C (893-532 ‰), NO3 (3.12-1 mg L-1), O.M (4.76-1 %), pH (6.8-7.5), PO4 (0.39-0.1 mg L-1), S (0.340-0.571 %), T.H. (321-489 mg L-1), TDS (450-276 mg L-1), Turb (6.3-3.4 mg L-1), C.W. (0.97-0.51 m sec-1), W.T. (13-7 D°).
