You're quite possibly right Jpinkster. As long as the diversion weir is kept open there shouldn't be much problem for migration. Heck, those fish may even just spawn right in the elbow(??). As you mention, the biggest problem will be stranding fish once they open the gates at the diversion reservoir. Should the weir ever be set permanently, it would block migration paths to the spawning creeks (Canyon, McLean, Silvester, etc.).
This proposal is much better for our trout friends than the McLean Creek reservoir, which I believe would be a permanent dam, correct?
The elbow river is the melting pot of historical stocking culture mixing with native populations in our province; brooks, bulls, cutts, rainbows, browns and whitefish. Hank Patterson could almost have caught one of his cutty-rain-brown's in the Elbow were it not for cross-breeding incompatibility haha.