Reservoirs make my list of pet peeves not really for what they are, but more for what they pretend to be. That is - Lakes. If the reservoir could just be a reservoir, which few actually do, and not attempt to masquerade as a lake, I would be satisfied. But no, it has to be Lake This and Lake That or Lake of the Blah, Blah and Blah, Blah, Blah Lake. Very few reservoirs actually just claim it with the name - Blank Reservoir.
All of this fake laking fools the innocent public into thinking that this body of water is, in fact, a lake. Au contraire, mon frere! These are no lakes. They are dirt pits filled in with water and it shows. Around these parts (Kansas City, MO), reservoirs have been fooling people for so long that many residents don't actually know what a real lake is. The definition of a lake specifies that the water be fresh, which almost immediately eliminates the majority of reservoirs. Have you ever been to "Lake" of the Ozarks? It has the visibility of about the length of one of Thumbalina's thumbs, has oil pools atop the water, litter-filled nooks/party coves, and is evacuated monthly for dangerous levels of ecoli (also known as poop). But, I digress...
My point is that lakes are clean, clear, and most often exquisite. They can be so large that you can't see across them. They have shipwrecks and undertow. They are often fed by cold springs. They have natural shorelines that are beautiful, not the edge of the hole that was dug with a mini-mall attached.
Perhaps my peeve is not with the reservoirs themselves, but with the bad name that they are giving lakes. So, go out and love a lake!
(Maybe I overdid this peeve a little bit, but reservoirs really bug me.)