It resembles a kame fan or a head-of-outwash and contains a layer of sand and gravel that is 60 metres (200 ft) thick.

[1] The first mill in Mifflin Township was built on a tributary of Tenmile Run by Jacob Swepenheiser.

[8] The Columbia County Natural Heritage Inventory designated Tenmile Run as a "locally significant site" in 2004.

[8] The stream is also designated as Class A Wild Trout Waters for a 3 miles (4.8 km) stretch from its headwaters downstream as far as the road T409.

[6] Tenmile Run flows through a palustrine forest consisting of hardwood trees and hemlock.

The forest's understory consists of Japanese barberry, low-bush blueberry, witch hazel, may-apple, white baneberry, Virginia creeper, viburnum, striped maple, partridgeberry, dogwood, and spotted wintergreen.

Birds living in the stream's watershed include worm-eating warblers, wood thrushes, ovenbirds, Eastern tufted titmouses, Eastern towhees, veeries, pileated woodpeckers, nuthatches, common yellowthroats, and American redstarts.

Other bird species found in the watershed include scarlet tanagers, black-capped chickadees, and black-throated green warblers.

The watershed's marshland is home to poison sumac, winterberry holly, multiflora rose, and other plants.