千人塚城ヶ池, Irrigation reservoir in Iijima, Nagano Prefecture, Japan
Sennin-zuka Shiroga-ike is an irrigation reservoir in the town of Iijima, Nagano Prefecture, Japan. The pond sits amid farmland and woodland, fed by the surrounding hills, and serves rice paddies across the local area.
Construction of the reservoir began in 1933 and was completed in 1936, during the early Showa period. It was built over the remains of an earthen hill fort that had stood on the site during the Sengoku period, centuries earlier.
Around the pond, cherry blossoms, hydrangeas, and autumn leaves draw visitors through the seasons. A mallet golf course and a campsite sit near the water, and families often spend a full day here.
The site can be reached by car or by taking a taxi from a nearby train station on the Iida Line. Opening hours change depending on the season, so checking ahead before visiting is a good idea.
The pond is designed to warm the water before it reaches the rice paddies, which helps the rice plants grow more strongly. This water-warming function is one reason the reservoir has been maintained so carefully over the decades.
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