The Ecology of Lake Izunuma-Uchinuma

The freshwater Izunuma-Uchinuma wetlands consist of two interconnected lakes: Izunuma and Uchinuma. The lakes cover a combined area of approximately 491 hectares, with Izunuma, the larger of the two, at 369 hectares. The lakes are surrounded by low-lying cropland and fed by multiple small rivers and streams, with the Hasama River serving as both the key inflow and outflow. The slow-current, nutrient-rich waters of Izunuma-Uchinuma support diverse aquatic vegetation, including reeds and water chestnuts.

As the lakes’ average depth is only around 0.8 meters, sunlight can reach the bottom, creating optimal conditions for the growth of aquatic plants. In summer, lotus flowers blanket the lakes’ surface, and local fishermen take visitors out for short boat rides to see the blooms up close. In winter, the lake rarely freezes over, making it an ideal habitat for the migratory birds that flock to the area.

Recognition under the Ramsar Convention

In 1985, the wetland was designated a Ramsar site for its global importance as a wintering ground for waterfowl and its role in ecological preservation.

The Ramsar Convention is a global agreement focused on the conservation and wise use of wetlands. It was established in 1971 in Ramsar, Iran, and emphasizes the value of wetlands as ecosystems that sustain biodiversity, help manage water systems, and serve as vital habitats for migratory birds.

Member nations agree to designate at least one internationally important wetland—known as a Ramsar site—and are expected to ensure its conservation and wise use. The convention also encourages cross-border cooperation, supports scientific research, and promotes education to deepen public understanding of wetland ecosystems.

Japan has more than 50 designated Ramsar sites, with Lake Izunuma-Uchinuma among the first in the Tohoku region to receive the recognition. Such sites play a vital role in preserving wetland ecosystems, protecting biodiversity, and mitigating climate change by acting as carbon sinks.

The environment surrounding the Izunuma-Uchinuma lakes includes rice fields, irrigation canals, and mixed-use farmland, forming a landscape where human activity and natural habitats closely interact. Local residents play an active role in conservation, including seasonal clean-ups and educational events for schoolchildren organized by community groups.