The sign you refer to is from when the open gate was closed.
HWY 39 is now open to Crystal Lake. Some point shortly after Crystal Lake, there is a closed gate, which is easily passed, but be careful-- the road conditions between the closed gate and HWY 2 are bad: many rocks, small and large, cover the entire road, and there is even a short (200 foot?) dirt section.
Here is a link to the Crystal Lake Recreation Area on Google Maps, if you want to see how far you have to go to reach it from your start point.