Wikipedia
The Lympha (plural Lymphae) is an ancient Roman deity of fresh water. She is one of twelve agricultural deities listed by Varro as "leaders" (duces) of Roman farmers, because "without water all agriculture is dry and poor." The Lymphae are often connected to Fons, "Source" or "Font," a god of fountains and wellheads. Lympha represents a "functional focus" of fresh water, according to Michael Lipka's conceptual approach to Roman deity, or more generally moisture.
Vitruvius preserves some of her associations in the section of his work On Architecture in which he describes how the design of a temple building ( aedes) should reflect the nature of the deity to be housed therein:
The character of the Corinthian order seems more appropriate to Venus, Flora, Proserpina, and the Nymphs [Lymphae] of the Fountains; because its slenderness, elegance and richness, and its ornamental leaves surmounted by volutes, seem to bear an analogy to their dispositions.
The name Lympha is equivalent to, but not entirely interchangeable with nympha, " nymph." One dedication for restoring the water supply was made nymphis lymphisque augustis, "for the nymphs and august lymphae," distinguishing the two as does a passage from Augustine of Hippo. In poetic usage, lymphae as a common noun, plural or less often singular, can mean a source of fresh water, or simply "water"; compare her frequent companion Fons, whose name is a word for "fountain," but who is also invoked as a deity.
When she appears in a list of proper names for deities, Lympha is seen as an object of religious reverence embodying the divine aspect of water. Like several other nature deities who appear in both the singular and the plural (such as Faunus/ fauni), she has both a unified and a multiple aspect. She was the appropriate deity to pray to for maintaining the water supply, in the way that Liber provided wine or Ceres bread.