I think it's still in consideration. I contacted WA County and they said they're not sure, but they think its likely too. They also sent me here:
http://www.tualatinbasinwatersupply.org/project_description.html
There are a couple different plans. I've emailed the project manager for the Hagg Lake effort. I should hear back pretty soon, and if I don't hear back, I'll call him. When I hear something, I'll post it here.