The parasite nanophyetus requires a snail as an intermediate host as I recall and can be transported by mammals wandering about. Nanophyetus is endemic to the Deschutes watershed for as long as anyone has known. That is apparently a major reason why none of the anadromous fish introductions have never taken well to natural production. The native cutthroat trout have co-existed with the parasite for just about forever, and presumably have a greater evolved resistance than any introduced fish stocks. I don't know if nanophyetus was historically endemic to the McAllister basin, but the Chinook salmon hatchery facility there was shut down due to reduced salmon survival attributed to nanophyetus. All it would take is for an infected raccoon or skunk to wander from the Deschutes, and eventually another to wander to the Nisqually basin to spread the infestation.

I don't know how much slough like conditions the snail requires, but the Deschutes is not characterized by that specific habitat type. But springs, with their attendant sloughs and vegetation, even if small, do exist in all three basins. I cringe to think of nanophyetus spreading further northward.

Some things described in the report indicate that things aren't looking good for steelhead, Chinook, and coho in PS for the foreseeable future.

Sg