Continuing south through Shizuoka Prefecture, the river drains a wide coastal plain noted for fruit and rice production.

With the occupation of Hamamatsu Castle by Tokugawa Ieyasu, considerable efforts were made to increase the revenues of Tōtōmi Province through creation of new rice fields with irrigation from the Tenryū River.

As depicted in contemporary ukiyo-e prints by artists such as Hokusai, travelers crossed the river on ferryboats, as the current was too fast and too deep for fording.

In cases of bad weather or high waters, they were forced to stay several days (or even several weeks) beside the river at post stations (shukuba) such as Mitsuke-juku.

After the end of World War II, the American occupation authorities ordered the dissolution of Nippon Hassoden, which was divided into regional power companies.

Central Japan came under Chubu Electric Power, which inherited the various dams and projects on the Tenryū River, all of which were located in Nagano Prefecture.

Meanwhile, at the same time, the vast amount of sand and silt trapped in various dams upstream have resulted in greatly lowered operational lives than originally projected.

The Tenryū River Valley is partially within the Tenryū-Okumikawa Quasi-National Park with the Tenryūkyō Gorge as a nationally designated Place of Scenic Beauty in Iida, Nagano Prefecture, Japan.