Line 182 may be a combination of various allusions.
Leman is an archaic English word for lover or paramour. However, this word was used by Sir James George Frazer in his chapters on Adonis, Attis and Osiris in The Golden Bough.
Lac Leman is the name by which Lake Geneva is known in Lausanne, Switzerland. And while certainly not an allusion that Eliot would expect his readers to catch, Eliot wrote part of "The Waste Land" while undergoing psychiatric treatment at Lausanne.
Many consider this to be an allusion to the Bible's Psalm 137. Compare line 182
182) By the waters of Leman I sat down and wept . . .
with Psalm 137, verse 1:
1) By the rivers of Babylon, there we sat down, yea, we wept, when we remembered Zion.
Indeed, it may be worthwhile to read the lamentations in the first 6 verses of Psalm 137
In The Tempest (act I, scene ii), where we already have been referred to earlier, Ferdinand says 'Sitting on a bank, weeping again the king my father's wreck, ... '
Another allusion may be to Jean-Jacques Rousseau's Confessions, Book IV. Rousseau wrote of a walk at Lake Geneva (also called Lac Leman) where he remembered, among other things, "Miss Vulson, who had been my first love." He wrote that he wept often and "How often, stopping to weep more at my ease, and seated on a large stone, did I amuse myself with seeing my tears drop into the water."
Eliot taught an extension course on Rousseau prior to writing The Waste Land.
Perhaps this line is also an allusion to the 1898 assassination of Empress Elisabeth of Austria.