The lake appears to have a self-sustaining kokanee population that spawns in the inlet and there might be some spawning on springs/seeps in the lake.
There was a fish screen on the outlet for some period of time. I understand it was there to prevent out-migration of trout stocked in the lake. Probably worked for any kokanee that might have decided to wander down Indian Creek to Lake Aldwell. I don't think anyone knows if any made it over/through the dam and out to the salt. The screen came out some time back because it was causing water level problems in the lake when it would plug up with debris.
Sockeye dip in to the Elwha and Dungeness. I don't know if any redds have been documented in the rivers. With the sockeye life cycle, neither river currently provides the habitat for sockeye development.
Closure of Sutherland will have an economic impact on the local sporting goods stores. Loss of the lake to fishing means folks in PA and Sequim have to drive to Anderson (frequent closures due to blue algae) or Leland (same problems) or some smaller lakes to the east or Pleasant Lake to the west. None of the lakes have a kokanee fishery like Sutherland.
From my perspective, the lake can be kept open for trout/kokanee fishing and the outlet monitored for any departing kokanee. I'm presuming the catchable size kokanee in the lake probably won't be the ones that might decide to out-migrate. IF sockeye start to show up 3 or 4 years down the road, then the restrictions placed on the take of wild salmonids in the basin could be applied to adult/mature sockeye that are looking for a place to spawn in the lake, the inlet, or Indian Creek. The rest of the basin can and should be managed for wild fish recovery.