[Introduction] In the watershed of the Ohkawa River in Miyagi Prefecture in the North East of Japan, a substantial amount of afforestation is being carried out. That is because people think the ruin of the forest vegetation causes the decrease of nutrients in the river water and consequently the decrease of coastal productivity. Furthermore, it has been suggested that organically-bound iron supplied by the river water will contribute to maintain the growth of phytoplankton in the coastal region (Matsunaga et al., 1998). The organic material is supposed to be fulvic acid and to originate in forest soil and organically bound iron is called fulvic acid-iron (FA-Fe). Furthermore, fulvic-like organic matter in the river is supplied by waste water of urban life (Takahashi et al., 2003). Therefore, we studied the FA-Fe origin of two rivers different watershed environments. We developed a GIS database to determine the land use of the watershed. [Materials and Methods] The study areas are located along the Ohkawa River and the Nanakita River in Miyagi Prefecture in the North East of Japan. The Ohkawa River originate in Mt. Toishi Yama and pours into Kesennuma Bay. On the other hand, the Nanakita River originate in Mt. Izumi Gatake and pours into Sendai Bay. It runs through Sendai City (population one million), where it is affected by waste water from urban area. River water samples were collected in the upper and the lower streams sites on each river from June to November, 2005. Waste water from urban area was collected. To study water quality, we determined pH, EC, and amount of fulvic acid-Fe (FA-Fe), dissolved iron (D-Fe) and total iron (T-Fe). The GIS database developed was used to determine the area of watershed and the land use of both the Ohkawa and Nanakita River regions. [Results] The total watershed area of the Ohkawa River was estimated to be 16,744 ha, including forest, agricultural, and urban areas of 12,179, 2,839, and 550 ha, respectively. The total watershed area of the Nanakita River was 22,303 ha including forest, agricultural, and urban areas of 8,090, 3,498, and 8,647 ha, respectively. The watershed area of the sampling site on the upper stream of the Ohkawa River was 29 ha, and was covered by forest vegetation. The watershed area of the lower stream site was 12,529 ha, (9,185, 2,235, and 179 ha, respectively). The upper stream one of the Nanakita River was 1,140 ha, (797, 117, and 10 ha, respectively). The lower stream one was 16,800 ha, (7,923, 2,661, 4,756 ha, respectively). The average concentrations of FA-Fe in the upper and lower stream water of the Ohkawa River and the Nanakita River were 0.001, 0.018mgL^-1, and 0.005, 0.056 mgL^-1, respectively. The D-Fe concentrations were 0.01, 0.027 mgL^-1, and 0.013, 0.068 mgL^-1, respectively and those of the T-Fe were 0.31, 0.12 mgL^-1, and 0.05, 0.30 mgL^-1, respectively. The EC of the upper and lower stream in the Ohkawa River were 73 and 114 ìScm^-1, and in the Nanakita River were 81 and 249 ìScm^-1. Both the pH and the EC of the lower stream water were higher than those of the upper stream. In the lower stream site of the Nanakita River, the EC was significantly higher than the rest and suggests that the site was affected by waste water from Sendai City. Except for the T-Fe of the Ohkawa River water, the concentrations of each form of iron in both of the lower streams were higher than in the upper streams. This tendency was much clearer in the Nanakita River water. To compare the proportion of land use area in the lower stream watershed, the forest area percentage of the Ohkawa River region (73%) was significantly higher than the Nanakita River one (47%) and urban area proportion of the Ohkawa River one (1.4%) was much lower than that in the Nanakita River one (28%). Also, FA-Fe has been considered to be originate in forest soil, but our results suggest that FA-Fe was supplied by the waste water of urban life. The actual concentration of FA-Fe, D-Fe, and T-Fe in the waste water of urban areas were 0.034-0.078, 0.063-0.108, 0.27-0.84 mgL^-1, respectively. All of the values were remarkably higher than that from upper stream water, and some also had higher concentrations than those of the lower stream water. From these results, we may conclude that organically bound iron in river water such as FA-Fe originates not only in forest soil but also in waste water from urban life.