### History of the Water Environment Improvement Model Project for Enclosed Coastal Seas - Miyagi, Osaka, Hyogo - April 2007 to the 2020s

### History of the Water Environment Improvement Model Project for Enclosed Coastal Seas - Miyagi, Osaka, Hyogo - April 2007 to the 2020s

#### 2007: Launch of the Model Project
Miyagi, Osaka, and Hyogo prefectures initiated a model project aimed at improving the water environment of enclosed coastal seas, targeting Sendai Bay, Osaka Bay, and Harima-Nada. The project aimed to address regional water pollution and achieve sustainable conservation of ecosystems. Technologies to reduce wastewater from aquaculture and suppress nitrogen and phosphorus discharges were introduced, improving oxygen deficiencies in coastal areas. Collaboration among local governments, companies, and research...

#### 2010s: Expansion of Applications
During the 2010s, the scope of applied technologies expanded, leading to notable outcomes. In Sendai Bay, new technologies promoting the decomposition of organic matter from aquaculture were introduced, reducing annual nitrogen discharges by 15%. Osaka Bay saw an expansion of artificial tidal flats and seaweed beds to 100 hectares, increasing the diversity of fish and crustaceans by over 20%. In Harima-Nada, advanced wastewater treatment systems improved water transparency, boosting tourism recovery...

Additionally, each prefecture developed a "Comprehensive Water Environment Improvement Plan," promoting unified efforts for improving the conditions of enclosed coastal seas across the nation.

#### 2020s: Current Status and Progress
**Miyagi Prefecture (Sendai Bay)**
By the 2020s, the Sendai Bay project, led by Miyagi Prefecture, progressed further. Collaborating with aquaculture operators, efforts to reduce wastewater and purify water quality were made, cutting nitrogen and phosphorus discharges by 25% compared to 2007. New microbial purification technologies were adopted, significantly enhancing oxygen levels in coastal waters.

**Osaka Prefecture (Osaka Bay)**
The "Rich Osaka Bay" project continued to expand, with artificial seaweed beds and tidal flats increasing further. Bottom sediment improvements advanced with materials independently developed by companies, restoring fishery resources. By 2022, fishery yields within the bay rose by 10% compared to the previous year.

**Hyogo Prefecture (Harima-Nada)**
Hyogo Prefecture, in collaboration with local companies, promoted coastal vegetation conservation and advanced wastewater treatment. By 2020, the vegetation area reached 300 hectares, enhancing biodiversity. Environmental conservation efforts boosted tourism, increasing visitors by 20% compared to 2015.

#### Future Prospects
These efforts have contributed to revitalizing regional economies and promoting tourism, with expectations for technology application in other regions with enclosed coastal seas. Under the Japanese government's "Comprehensive Marine Environment Policy," further technological innovations and cooperation with local residents are anticipated. The achievements of Sendai Bay, Osaka Bay, and Harima-Nada remain significant models for realizing a sustainable society and are expected to continue gaining attention domestically and internationally.