The gulls in the front are ring-bills. We get thousands of them at the lake in the winter. We also get a few other species of gulls here & there. The two gulls in the back with black on their heads are Franklin's gulls. Just passing thru during their winter migration. Photo is not crooked, the spillway is on a slant.
Franklin's gull (Leucophaeus pipixcan)
Ring Billed gull (Larus delawarensis)