surname, name of certain rivers
涂 is a rare kanji used mainly as a surname and in the names of certain rivers. Its core idea is tied to water or a waterway, but its standalone meaning is narrow and name-specific.
涂 combines 氵 (water) with 余, which likely contributes the sound. The character is associated with water-related names, but its detailed historical development is uncertain.
Water 氵 beside 余 suggests a river or waterway. Picture a river named after the Yu family, flowing through their land.
For ト, imagine a toe dipping into the river named 涂: toe -> ト, and the water is cool.