The creek then receives an unnamed tributary from the left and flows south for more than a mile and its valley deepens.

The creek's valley then becomes much shallower as it turns south-southwest and then south, crossing Pennsylvania Route 118 near the community of Kyttle.

[1] Upstream of Pennsylvania Route 118, the concentration of alkalinity in Arnold Creek is 4 milligrams per liter.

Downstream of Pennsylvania Route 118, the alkalinity concentration in the creek increases to 5 milligrams per liter.

[1] Pennsylvania Route 118 crosses Arnold Creek 2.7 miles (4.3 km) upstream of its mouth.

[2] Arnold Creek is entirely in the United States Geological Survey quadrangle of Sweet Valley.

[9] Two sections of Arnold Creek are considered by the Pennsylvania Fish and Boat Commission to be Class A Wild Trout Waters.

One section is approximately 2.3 miles (3.7 km) long and runs from the creek's headwaters to Pennsylvania Route 118.

The other section is approximately 2.7 miles (4.3 km) long and runs from Pennsylvania Route 118 to the creek's mouth.