classic waka stream

from the deep mountains
the water that comes falling down—
seeing its color
I have come to know at last
that autumn has reached its end

Meaning
Seeing the color of the water that falls from the deep mountains, I have come to realize that autumn has reached its end.
Commentary
Book Five Autumn Poems (Part Two)

When, in the reign of Emperor Kōkō, an order was given to present ancient poems, the poet wrote the poem beginning “Tatsuta River, with crimson leaves flowing,” and composed this in the same spirit.

Without directly naming the autumn leaves, the poet expresses them through the color of the water at the end of autumn, from which one understands that the leaves have fallen and are flowing downstream. In this way, the poem conveys a quiet sorrow at the passing of autumn.
Author
Fujiwara no Okikaze
Source
Kokin Wakashu
Other