After a few tenths of a mile, it turns southwest, crossing Pennsylvania Route 412 and reaching its confluence with Saucon Creek.

[4] A reach of Polk Valley Run is designated as an impaired waterbody due to siltation from agricultural activity.

Channelization and rebuilding a culvert carrying the stream under Main Street have been proposed as flood control measures.

[8] The Hardyston Formation and felsic to mafic gneiss is present in the watershed of Polk Valley Run.

[9] The stream's valley is also home to some quartzite that is slightly atypical for the region: brittle and gray with pebbles up to three eighths of an inch in diameter.

[7] The watershed of Polk Valley Run is mostly in Lower Saucon Township, but a small part of it is in Hellertown.

[11] Upstream of the gauging station in the lower reaches of Polk Valley Run, more than three quarters of the stream's watershed is forested.

[14] Wild trout naturally reproduce in Polk Valley Run from its headwaters downstream to its mouth.

Plant species in the area include sycamores, pear trees, red cedars, and willows, as well as wildflowers and seasonal grasses.

[11] As of 2013, the Saucon Creek Watershed Association is committed to improving riparian buffers along Polk Valley Run to reduce streambank erosion.