In 1934, when the area was envisioned as Japan's first national park, it was far smaller than the expanse of today. Sixteen years later, in 1950, an expansion would seek to include other iconic sites in the region, bringing the total area roughly up to that of the present-day. Setonaikai is the biggest national park in Japan. In 1996,
Itsukushima Shrine (in Hiroshima prefecture) was registered as a “cultural site of world heritage” by UNESCO. It is known as one of the top three “most scenic spots” in Japan. In the 1960s and 1970s, a period of rapid economic growth was fueled in Japan, resulting in industrial contamination of the surrounding environment. In both fresh and ocean waters, unmonitored chemical runoff led to reduced water quality, mainly due to area farms’ use of synthetic fertilizers, pesticides, and herbicides. Detrimental levels of heavy metals began to rise, gradually affecting the natural food chain and greater ecosystem. Starting in the 1980s (and continuing on into the present day), water quality has been drastically improved; stricter regulations on chemical use and runoff have been enforced, as well as advancements in technology, namely a high-performance sewage disposal. ==Climate==