Kazan' at the end of the eighteenth century:
the Kaban: the lake in the center right part of the image
the Kazanka: the river flowing from right above the map legend, up and to the right (it eventually meets the Volga)
image source: N. F. Gulianitskii, Moskva i slozhivshiesia russkie goroda XVIII-pervoi poloviny XIX vekov (Moscow: Stroiizdat, 1998)
Kazan' now:
the Kazanka is now virtually part of the Volga, and a "vodokhranenie," or reservoir; the Kaban has expanded to become a single larger lake, rather than two lakelets separated by a canal.
"There are three different species of water in Kazan, and the three degrees of comparison of the adjective bad, serve perfectly to give an idea of each of these species. The first, which is merely bad, is the water of the Kaban, a lake that furnishes the whole town with this element. I have certainly been indulgent in the cognomen I have attached to it; to prove it, I need but say that it is a stagnant pool, which during the summer months becomes putrid, and swarms with animalcules. Even in winter it has an unpleasant taste, and if left for a short space of time in a heated room, it becomes absolutely undrinkable . . . . The second species is obtained from the wells, which are numerous in Kazan. This water is worse than the first, and although it may, in cases of necessity, be employed for the kitchen, it is totally unfit for any other use, and in particular for tea, which both the Russians and Tartars drink in great quantity. . . .The third species of water is that of the river Kazanka; this is bad to a superlative degree. It is impossible to employ it in consequence of the great quantity of sulphate of lime it contains. . . . In a word, the inhabitants of Kazan employ this water for two purposes only—for washing horses and drowning kittens, nor do I think it can be adapted to any other."
from: Edward Tracy Turnerelli, Russia on the Borders of Asia. Kazan, the Ancient Capital of the Tatar Khans; with an account of the province to which it belongs, the tribes and races which form its population, etc., Vol. 1 (London: Richard Bentley, 1854), 249-51