The researchers studied the water quality and aquatic plants in the upper Taihu Lake watershed. They found high nutrient levels in the water, leading to excessive plant growth. Water quality was poor in most areas, affecting the diversity of aquatic plants. Water hyacinth and duckweed were common, while submersed plants were declining. Different types of nutrients in the water and sediment influenced the types and distribution of plants. Rivers and the lake had distinct differences in water quality factors.