Hai Phong city midland plains interspersed has hills and low lean toward the Oriental Sea with many major rivers flowing from the Northwest to the Southeast. The main rivers in Haiphong include Da Bac River, Cam River, Lach Tray River, Van Uc River, Thai Binh river and Bach Dang River. There are also many small rivers and some lakes located in the urban area. Survey results of phytoplankton in some typical characteristical waters in Hai Phong city in April and June/2011 identified 96 species of algae belonging to 4 divisions: Bacillariophyta, Chlorophyta, Cyanobacteria and Euglenophyta. Phytoplankton number of species in the river area is higher than in the pool area. In the phytoplankton, appeared a group of indicator species for water quality organically polluted in the genus as Oscilllatoria, Phormidium Mycrosystis of Cyanobacteria
Crucigenia, Scenedesmus of Chlorophyta
Euglena, Phacus of Euglenophyta. The density of the Phytplamkton group at the lake ranged from 1417.5 Cell/l to 4422.6 Cell/l and in the river ranged from 1190.7 Cell/l to 12474.0 Cell/l. In which, the density of Bacillariophyta accounted for the highest percentage, followed by the group of Chlorophyta, Cyanobacteria and Euglenophyta. Diversity index (H) ranged from 2.22 to 2.84 expression on the water quality of lakes and rivers of this region slightly contaminated. Pollution levels has the differences between water bodies and areas. Environmental water in the Hai Phong is little polluted and polluted by human activities.