Eleven long, narrow lakes running north to south, and Rochester drinks from two of them, Hemlock and Canadice, which is why there's nearly nothing built on their shores.
There are eleven of them, long and narrow and running roughly north to south, and none is wider than 3.5 miles. Seneca is the big one: 38 miles long, 618 feet deep, holding roughly half the water in the chain, with underground springs that keep it from freezing over in most years, Geneva at the north end and Watkins Glen at the south. Cayuga is a shade longer, just under 39 miles, and 435 feet deep, with Ithaca at the bottom and Seneca Falls at the top. Both go so deep that the bottom is below sea level, which is a strange thing to think about from a dock.
Out west the lakes get small and the water gets strict. Hemlock is a translation of the Seneca name, O-neh-da Te-car-ne-o-di; it's seven miles long, and Rochester has been drinking from it since 1876, which is why the hundred-odd cottages and five hotels came down starting in 1895. Canadice, from the Seneca ska-ne-a-dice, meaning long lake, is the smallest of the eleven and has fed the city since 1919: no houses on the shore, no boats over 17 feet. Conesus, eight miles long in Livingston County, is the one where residents light flares all the way around the shoreline every July 3 for the Ring of Fire.
Keuka is the odd one out, Y-shaped where the others are long and narrow, hence its old name, Crooked Lake; Keuka is a Seneca word for canoe landing, or lake with an elbow, and vineyards have surrounded it since the mid-1800s. Canandaigua, 15.5 miles long, is the westernmost of the major lakes, and the city at the north end drinks from it. Skaneateles sits at about 863 feet, higher than the rest, so it's sometimes called the Roof Garden of the Lakes, and a mailboat still serves the cottages. Owasco drains the biggest watershed of the eleven, and Otisco, the easternmost, was dammed in 1869 to feed the Erie Canal.
It's a crewneck with a lake on it. The Keuka crewneck in Blue Spruce is for people who will explain the Y-shape whether you ask or not. The Conesus crewneck in Conesus Blue is for the Ring of Fire crowd. And the Skaneateles crewneck in Strawberry Cloud is for anyone who can say it: SKAN-ee-AT-ləs, or SKIN-ee-AT-ləs if you're from there.
Sources: en.wikipedia.org · en.wikipedia.org · en.wikipedia.org · en.wikipedia.org · en.wikipedia.org · en.wikipedia.org · en.wikipedia.org · en.wikipedia.org · en.wikipedia.org · en.wikipedia.org · en.wikipedia.org