It would be a poetic way to name a distant starting place for something (not necessarily with water). His etymology would be in the hontanar voice (origin of a spring). See hontana.
HONTANANZA Spelling error by LONTANANZA Being in the distance, back and forth. Figuratively, in the distance of time, it is a long time ago : In the lontananza. Some synonyms, words or similar expressions may be in the distance, in the background