I thought the brook trout were stocked in the White River for brown trout food. Mike's right, but what I've heard was in the pre 9/11 days people would catch LARGE Rainbows near the dam at night fishing vertically from pontoon boats etc. That area likely still holds lots of large bows, but that area is off limits to boats nowadays.
We'd have to look at the stocking data, but I think AGFC is STILL stocking rainbows in the spring each year. Hey man if they're gonna dump em in Amon's Lake, they might as well throw a few in BSL.