Details
Start from the Middle Fork Trailhead lot.
Follow the trail access path through the trees to the suspension footbridge across the river. Immediately after crossing, turn right on the Pratt River Connector Trail, following the river downstream.

The new trail is smooth and easy. Parts of it repurpose historical
vehicle tracks.

At 3.4 miles, you will reach a seemingly arbitrary point where
the trail maintainers stopped. Whether apparent or not, they have
connected to the historical Pratt River access road, over which logs
were once stripped out of the valley on an industrial scale. Below this
point, the thick-skinned and adventurous might dive into the dense
river brush, looking for the site of the historical cable crossing
of the Middle Fork Snoqualmie River. But that exercise would be
unpleasant, possibly futile, possibly dangerous. Your better
choices are to continue on the
Pratt River Trail or return.