As far as I know, there is no construction being done on the Roberts Tunnel. The Blue is running because Lake Dillon is currently ~95% of capacity and they are creating more storage in anticipation of the upcoming runoff. There is no need to send the water down through the Roberts Tunnel with all the Front Range reservoirs full and the rivers raging.
I've been told we could see flows around 2K on the Blue this summer, but that really depends on what the weather does between now and early June.