For if the old cress-woman, the sole inhabitant of that secluded valley, had been inclined to make observations, she could not have failed to perceive that irriguous as were the windings of the brook, Miss Margaret and her friends preferred following them to their utmost.
-- Catherine Grace Frances Gore, "Blanks and Prizes, Or The Wheel of Fortune," Tait's Edinburgh Magazine
As nothing, at the opening of Spring, can exceed the luxuriant vegetation of these irriguous valleys; so, no term could be chosen more expressive of their verdure.
-- William Beckford, Vathek
Irriguous comes from the Latin word irrigāre meaning "to wet" and the suffix -ous which turns a verb into an adjective, like nervous.