The ranges of the physicochemical and hydrological parameters in Jajroud Stream are listed in Table 5 and 6. Mean water velocity was 120 cm. s-1 in a Jajroud stream with a minimum of 100 cm. s-1 in ST3 and a maximum of 142cm. s-1 in ST1. Water depth rarely exceeded 75 cm. The minimum and maximum water temperature recorded was 4ºC during November and 18.7ºC during June respectively, with an average of 11.52ºC. Minimum dissolved oxygen concentration, 11.3 mg.l-1, was recorded during June and maximum dissolved oxygen concentration, 13.9 mg.l-1 occurred during February. Dissolved oxygen values were above saturation and BOD5 was low at all times at all sites. The differences in dissolved oxygen concentrations and BOD5 between the stations were not significant (p > 0.05). The amount of NO3-N ranged from 0.26 mg. l-1 to 0.68 mg. l-1 and PO4-P ranged from 0.13 mg. l-1 to 1.33 mg. l-1 during the study period. The PO4-P values were generally low at all sites. NO3-N and PO4-P concentrations increased from upstream sites toward downstream. The use of agricultural fertilizers and urban sewage are believed to increase the Nitrate Nitrogen.
A total of 92 macrobenthic fauna species represented by five diverse groups were encountered, of which Diptera were the most dominant group with 38 species and contributed numerically up 38% of the population. Ephemerptera consist of 23 species and contribute to42% of the total fauna population. Plecoptera consist of 15 species and contribute