"but this spring I tried it out right below the dam the weekend before walleye season opened and did VERY well with eyes and white bass. For a while there it was a fish every other cast. Do they normally stack up like?"
That's why you caught them the season wasn't in. If the fish were stacked like that during the season it wouldn't take long for the word to get out. They have always did good the first couple of days of the eye season than it slacks off. There are periods of the year when the fishing can be really great in the river and other times it can be a dead sea.
When I was a lot younger you had to have at least 5 or 6 dozen crawlers every time you went to the river to fish. It resembled the spring time fishing at Pymatuninng when the eyes make the spawning runs. If you got there late you had to wait until some one caught thier limit just to get a spot to fish.
Keep fishing it as much as you can and you'll find the pattern to catching them year round. An old timer that use to fish the river with a fly rod for eyes told me one time that the fish haven't gone any where, they're still there, it's your job to present a bait that the fish want. Just make them want to attack your bait.